El Captain only for laptops?

[dyn]

Understand PDF, postscript and modern memory management and you'll understand why the memory usage of Preview is normal. PDF/Postscript are not simply files you open and view, it takes more than that. You'll be having the same issue with any PDF software on any platform.

In Windows 10 the memory usage is 15%, on OS X it is 6.25% and on my OpenSUSE box it is 8.5%. In all cases I'm using the same file (an eBook with 589 pages) and the built-in PDF viewer. Performance and rendering wise (oh my, a hint!) they are all the same. The memory will increase a lot when you start to open more files. Like I said, it is just the nature of PDF/Postscript and has nothing to do with the app you use for reading/editing them.

 

[sibcc]

Like I said, that's how it worked in the 90s. It's not how it works now. And most definitely not with files like PDFs due to their very nature.


You want low mem usage? Don't use PDFs! They are a memory hog on any system and they are far far far faaaaar worse when you print them. Watch the memory usage and the spooler. It is like Jacks beanstalk...huuuuuuuuuuge.

While I agree wrt pdf memory usage and have long disliked the format, it's impossible to do without pdfs for most people. At times, I may have 30-40 books and research papers open. That said, I also use Clearview for its tabbed interface and Skim for general use.

 

[crashoverride77]

I guess that`s the whole point of it; 10.10 never gave me any issue, yet 10.11 is problematic, equally vice versa for others. All being equal we should all have the same upgrade experience, barring third party software & hardware. Obviously this is not the case. I may do a clean install, however this is time consuming versus rolling back to 10.10.5

Q-6

10.10 never gave me any real issues too, and El Capitan is still miles better. As someone above mentioned, care to list some of those issues, especially from a casual consumer standpoint?

The OP seems to be a casual consumer otherwise he wouldn't ask his friends if he should upgrade.
For people to than come in here and claim El Capitan sucks etc is crazy. Telling people especially regular consumers to not upgrade to El Capitan is ridiculous and categorily false advice. El Capitan in beta 1 was already a million times better than 10.10.5 can ever hope to be. In regards to OS speed metal actually seems to work on OS X, iOS not so much.

 

[crashoverride77]

Those screenshots are completely meaningless. Memory is there to be used and any proper OS will use it. Any proper OS will also turn things down a notch when memory isn't available in heaps. As long as performance is good, memory pressure is fine (green) and it works stable you needn't worry. I see a lot of people here who need to update their IT knowledge to 2015 instead of still living in the 90s. Even Windows now takes full use of the memory and task manager will therefor show "high" memory usage by apps so going Surface Pro 4 will give you the very same memory usage results as with OS X.

And AirDrop...when did that ever work properly? They need to start getting that up to a reliable level.

Crazy right, it has been 2+ years since Mavericks introduced the new ram management and people still claim OS X eats ram. Unused ram is useless ram as had been said a million times already.
Air drops seems to be much better since they switched back to mydnsresponder, for me at least. What are your issues, it not showing up or it failing to send data?

 

[Ebenezum]

Get out of here with that. There is literally zero reasons to stay on Yosemite unless you like more bugs, lag and less performance, I mean a lot less performance. 😕

I agree that Yosemite is slower than El Capitan but when compared to Mavericks its different story. While Mavericks has some bugs its in my experience much more solid compared to 10.10 and 10.11. I see little point upgrading from Mavericks at this point unless one uses software that requires newer OS.

10.10 never gave me any real issues too, and El Capitan is still miles better. As someone above mentioned, care to list some of those issues, especially from a casual consumer standpoint?

I gave examples of such issues in post 4.

For people to than come in here and claim El Capitan sucks etc is crazy. Telling people especially regular consumers to not upgrade to El Capitan is ridiculous and categorily false advice. El Capitan in beta 1 was already a million times better than 10.10.5 can ever hope to be. In regards to OS speed metal actually seems to work on OS X, iOS not so much.

Not exactly "sucks" it just was released way too early and it has too many bugs. When Apple fixes it enough I might recommend it but that will take time (probably at least until 10.11.3 is released) and I cannot recommend installing it at this point.

 

[Queen6]

10.10 never gave me any real issues too, and El Capitan is still miles better. As someone above mentioned, care to list some of those issues, especially from a casual consumer standpoint?

The OP seems to be a casual consumer otherwise he wouldn't ask his friends if he should upgrade.
For people to than come in here and claim El Capitan sucks etc is crazy. Telling people especially regular consumers to not upgrade to El Capitan is ridiculous and categorily false advice. El Capitan in beta 1 was already a million times better than 10.10.5 can ever hope to be. In regards to OS speed metal actually seems to work on OS X, iOS not so much.

No one is suggesting that 10.11 should be completely avoided, equally it has issues for some as this forum clearly illustrates. By waiting until .1/2 it may save as you put is the "casual consumer" some "headache". Ultimately there is little compelling to move to 10.11 unless 10.10 was problematic. In my case is was is/was not, for some stability is the priority.

For me a lot broke moving to 10.11, forcing a clean install, which is generally not required with OS X. This is time consuming, rolling back to 10.10.5 is certainly a much faster process, equally I want to see how the new OS performs and what if any compatibility issues I may incur, prior to upgrading primary systems.

Depending on your usage a little caution, is not such a bad idea, ultimately no one is going to care what OS you use, only your output...

Q-6

 

[Queen6]

Not exactly "sucks" it just was released way too early and it has too many bugs. When Apple fixes it enough I might recommend it but that will take time (probably at least until 10.11.3 is released) and I cannot recommend installing it at this point.

My thoughts exactly Apple raced to the deadline, resultantly QC suffered. I will likely now stick with this Mac on 10.11 and wait on the later point releases for the others. I need a smooth transition as per all other OS X releases, not to eradicate the drive...

Q-6

 

[mag01]

Regarding the Preview memory usage when viewing PDF files in El Capitan.
I did perform a quick comparison between Yosemite (10.10.4) and El Capitan (10.11.1 Beta 4) that I've got installed here on separate partitions.
I used 2 simple PDF files, size 1,3 and 1.5 MB, the smaller one contained 2 pictures while the larger one just 1, otherwise they were both text only - about 300 pages of text in both cases

In Yosemite, after opening them the RAM usage was about 45-50MB, after scrolling to the end and back many times the RAM usage was around 60-70 MB (depending on which one of those 2 files was open), never higher.
Scrolling is very quick, no issues with anything like lagging, no rendering issues.
Trying to select a piece of text (for copy&paste somewhere else) is immediate.

In El Capitan, after opening the RAM usage was pretty much identical to Yosemite, however after scrolling to the end for the 1st time the RAM usage jumped to approx. 500 MB, after scrolling back to the beginning it went up by another 500 MB, then again another 500 MB after scrolling to the end for the 2nd time and finally another 500 MB after scrolling back to the beginning for the 2nd time. This means 2 GB at this point. After reaching this point the RAM usage didn't increase anymore finally.
Scrolling seems quick as well, but there are some occasional rendering issues when the text first appears blurry and you have to wait a little before it sharpens to the final form.
Trying to select a piece of text (for copy&paste) first results in few (in my case about 20) seconds of the famous spinning beachball gag that everyone loves to watch over and over again. Further selections are finally immediate.
Sure, that's perfectly normal 🙄

 

[KoolAid-Drink]

Get out of here with that. There is literally zero reasons to stay on Yosemite unless you like more bugs, lag and less performance, I mean a lot less performance. 😕

Disagree. 10.11.0 IS buggy. Choppy performance, TM doesn't work properly, and sluggish. Reminds me of 10.9.0.

Yosemite was smooth right off the bat for me. And, yes, that was on a cMBP, not a rMBP. I definitely had rock solid performance with Yosemite.

 

[Queen6]

Regarding the Preview memory usage when viewing PDF files in El Capitan.
I did perform a quick comparison between Yosemite (10.10.4) and El Capitan (10.11.1 Beta 4) that I've got installed here on separate partitions.
I used 2 simple PDF files, size 1,3 and 1.5 MB, the smaller one contained 2 pictures while the larger one just 1, otherwise they were both text only - about 300 pages of text in both cases

In Yosemite, after opening them the RAM usage was about 45-50MB, after scrolling to the end and back many times the RAM usage was around 60-70 MB (depending on which one of those 2 files was open), never higher.
Scrolling is very quick, no issues with anything like lagging, no rendering issues.
Trying to select a piece of text (for copy&paste somewhere else) is immediate.

In El Capitan, after opening the RAM usage was pretty much identical to Yosemite, however after scrolling to the end for the 1st time the RAM usage jumped to approx. 500 MB, after scrolling back to the beginning it went up by another 500 MB, then again another 500 MB after scrolling to the end for the 2nd time and finally another 500 MB after scrolling back to the beginning for the 2nd time. This means 2 GB at this point. After reaching this point the RAM usage didn't increase anymore finally.
Scrolling seems quick as well, but there are some occasional rendering issues when the text first appears blurry and you have to wait a little before it sharpens to the final form.
Trying to select a piece of text (for copy&paste) first results in few (in my case about 20) seconds of the famous spinning beachball gag that everyone loves to watch over and over again. Further selections are finally immediate.
Sure, that's perfectly normal 🙄

For some Preview is just an occasion use application, in my role Preview is a high frequency use application for me reviewing/referencing a myriad of technical documents & standards. I have done a clean install of 10.11.0 predominately as it was the only way to get Apple`s "Mail" to function correctly.

Preview is still consuming significant amounts of RAM versus the usage (before all the memory zealots chime in, I know how OS X works, equally one document, one application consuming by far the vast majority of the systems RAM, forcing paging makes no sense) I can copy text out without any Beachballs. Opening a second engineering standard resulted in more of the same with close to 8Gb of memory usage (5Gb comprised) add in a 3rd & 4th document the obvious occurs OS X is forced to page the excessive data in RAM to the SSD, net result, performance is degraded with Preview becoming choppy, with delay in selecting text especially in Fullscreen.

In total 4 documents consuming over 20Gb of RAM is far from acceptable, add in Mail, Calendar, Safari, Microsoft Office, proprietary engineering applications results in significant slowdown of the system. Same usage pattern/workflow on 10.10.5 did not result in any significant slowdown of the system, with significantly more documents open.

Apple has also depreciated some settings in Preview that may work for some, and will frustrate others. Unfortunately Skim is also exhibiting higher RAM memory usage, so the issue may be deeper than solely Preview 8.1, and as other are observing the same issue with Preview, it`s not an isolated case.

FWIW high end 2014 rMBP

Q-6

 

[mag01]

Yes, sure the current Preview behaviour is far from normal. I don't even understand how someone can even try to explain an obvious issue as normal behaviour. 🙄
Regarding the mentioned beachballing - I performed those tests at 2012 MBA with just Core i5 CPU where such kind of issues is much more visible. At some much powerful configurations such as yours this may pre practically nonexistent.

Nonetheless, El Capitan is in general still a better option for me than Yosemite where I had few more annoying issues (especially with VPN connections and mDNSResponder) that seem to be fixed in El Capitan. Also, the current 10.11.1 Beta seems to be a good step forward from the 10.11.0 release. Definitely less buggy, some apps that kept crashing at 10.11.0 don't crash anymore, and it also feels snappier overall :-D

 

[Queen6]

Yes, sure the current Preview behaviour is far from normal. I don't even understand how someone can even try to explain an obvious issue as normal behaviour. 🙄
Regarding the mentioned beachballing - I performed those tests at 2012 MBA with just Core i5 CPU where such kind of issues is much more visible. At some much powerful configurations such as yours this may pre practically nonexistent.

Nonetheless, El Capitan is in general still a better option for me than Yosemite where I had few more annoying issues (especially with VPN connections and mDNSResponder) that seem to be fixed in El Capitan. Also, the current 10.11.1 Beta seems to be a good step forward from the 10.11.0 release. Definitely less buggy, some apps that kept crashing at 10.11.0 don't crash anymore, and it also feels snappier overall :-D

Am waiting on 10.11.1 to see if it helps resolve some issues. Never been forced to do a clean install previously, equally I suspect waiting on the .1/.2 release will mitigate that significantly. Opposite for me never had a problem with my VPN`s on 10.10.5, or any other version of OS X, moving to 10.11.0 wiped them out, nor could they be reestablished. Took several days with the VPN provider to come up with a different DNS before I could get them back up on line.

Q-6

 

[dyn]

Crazy right, it has been 2+ years since Mavericks introduced the new ram management and people still claim OS X eats ram. Unused ram is useless ram as had been said a million times already.

OS X being a UNIX has always done that. There have been some tweaks of the system along the line though but no more than that.

Air drops seems to be much better since they switched back to mydnsresponder, for me at least. What are your issues, it not showing up or it failing to send data?

AirDrop between iOS devices seems to be working ok for most of the time but when it doesn't work I either don't see the device or there are issues when sending data (timeouts, taking really long, etc.). Between Macs something similar and Mac-iOS doesn't seem to be working at all, except for one Mac where it works on occasion. Reliability simply isn't there no matter the settings, etc. Not that I mind, I just use the good old way of network drives plus there is iCloud, OneDrive, etc. 🙂

Yes, sure the current Preview behaviour is far from normal. I don't even understand how someone can even try to explain an obvious issue as normal behaviour. 🙄

Welcome to reality where PDF and PostScript eat up any memory you have just as they loves disk space. So yes, that behaviour is normal, just not acceptable and especially not something Apple can do anything about (the format belongs to Adobe or the ISO if you are using the open standard version). It requires a complete redesign of the format which won't be easy (Microsoft tried with xps and failed thanks to PDF being so immensely popular). The advantages of the format still outweigh its disadvantages which is why it is used almost everywhere and thus we'll have to deal with it/accept it. One could always use ODF or OOXML since these won't eat up memory and disk space. Unfortunately they are editable unlike PDF.

Btw, the behaviour is noticeable with Preview, Skim, PDFPen, Adobe Reader (Win+OS X), Adobe Acrobat (Win+OS X), Win8/8.1/10 PDF viewer and the built-in viewers in Ubuntu and OpenSUSE (I think in both cases this was Evince). At least those are the ones I've tested. It starts out with already quite a lot of memory taken up when you open the PDF and will get worse once you start scrolling. When you print it gets to laughable sizes. I've had printers take half an hour to print a small 20 page PDF document that was like 99% text. When you start implementing pictures things can get even stranger. Scanning to PDF is similar.

The only real difference I've seen between Yosemite and El Capitan concerns scrolling PDFs: it's smoother in El Capitan.

 

[Queen6]

OS X being a UNIX has always done that. There have been some tweaks of the system along the line though but no more than that.


AirDrop between iOS devices seems to be working ok for most of the time but when it doesn't work I either don't see the device or there are issues when sending data (timeouts, taking really long, etc.). Between Macs something similar and Mac-iOS doesn't seem to be working at all, except for one Mac where it works on occasion. Reliability simply isn't there no matter the settings, etc. Not that I mind, I just use the good old way of network drives plus there is iCloud, OneDrive, etc. 🙂


Welcome to reality where PDF and PostScript eat up any memory you have just as they loves disk space. So yes, that behaviour is normal, just not acceptable and especially not something Apple can do anything about (the format belongs to Adobe or the ISO if you are using the open standard version). It requires a complete redesign of the format which won't be easy (Microsoft tried with xps and failed thanks to PDF being so immensely popular). The advantages of the format still outweigh its disadvantages which is why it is used almost everywhere and thus we'll have to deal with it/accept it. One could always use ODF or OOXML since these won't eat up memory and disk space. Unfortunately they are editable unlike PDF.

Btw, the behaviour is noticeable with Preview, Skim, PDFPen, Adobe Reader (Win+OS X), Adobe Acrobat (Win+OS X), Win8/8.1/10 PDF viewer and the built-in viewers in Ubuntu and OpenSUSE (I think in both cases this was Evince). At least those are the ones I've tested. It starts out with already quite a lot of memory taken up when you open the PDF and will get worse once you start scrolling. When you print it gets to laughable sizes. I've had printers take half an hour to print a small 20 page PDF document that was like 99% text. When you start implementing pictures things can get even stranger. Scanning to PDF is similar.

The only real difference I've seen between Yosemite and El Capitan concerns scrolling PDFs: it's smoother in El Capitan.

The point point you are missing is that the memory usage of Preview in 10.11 is significantly greater by several magnitudes than 10.10.5 Nor I am not stupid I understand PDF/postscript etc. What find difficult to rationalise is how the same 2.7Mb 98 page document on 10.10. 5 after a single scroll through in fullscreen memory usage grows to 144Mb, yet mirroring the same in 10.11.0 results in a usage of 2.73Gb, ultimately this results in a depreciation of Preview`s performance, given enough documents & applications the system slows, as for memory pressure it obviously rises.

Anyone who has both 10.10 & 10.11 can replicate the same symptoms with ease. My current 10.11.0 drive is a clean install with very little this party application installed, certainly no application that will effect Preview. We are not talking about 10%-15% memory consumption we are talking about exponential consumption by a single application. This is nor to say that 10.11 does not bring benefits, it does, equally it`s also bringing some baggage...

Q-6

 

[dyn]

I'm not missing that point, you simply fail to understand what PDF/PS is and how OS X memory management works nor do you seem to understand the basics of El Capitan (it's all about performance and stability).

PDF/PS are basically the same as any programming/scripting language. You need to compile these in order to get what you are seeing. There is some compression but this is not applied to all elements in a PDF which is why it uses quite a lot of disk space compared to other file formats (such as xps, ODF, OOXML). It builds up things as you go (read: when scrolling) and since everything happens in memory (it's fast and it's temporary which is exactly what RAM is for) you see a. a huge memory footprint and b. an increase in memory usage when doing things like scrolling.

Compared it to Safari on iOS: if memory is low and you switch to a tab it needs to be reloaded. A lot of people find this annoying and demand Apple put more memory in the iOS devices. The same happens in OS X: if you have a lot of memory that is freely available it will appoint this to an app asking for it. That way you see less reloading of pages when you do things like scrolling a PDF document in Preview. If memory isn't freely available then the app gets the very basic amount it needs and you'll see a lot of reloading of pages when you scroll. El Capitan main feat is performance so it isn't strange that you see higher memory usage from apps. You can test this if you have a vm running El Capitan: see what happens when you increase and decrease the memory. In my case I tested with another eBook and my iMac with 16GB of RAM shows 806MB of memory usage by Preview whereas my El Capitan vm with only 2GB of memory merely shows 40.1MB for that very same file. After scrolling this is 1.36GB on the iMac and 128.3MB for the vm. The difference is that memory pressure on the iMac is in the green but in the vm it is yellow or in other words: the vm might have the lower memory consumption with Preview but that's because it is seriously lacking memory as the memory pressure graph clearly shows. Due to that the vm is less performant than the iMac. The higher memory footprint in fact means more performance. And what was El Capitans main feat...? 😉

Btw, when quitting the app it will return the memory to the OS. If it isn't needed than it will still keep the contents of the app in case you open the app again. This is done to make the app more performant. However, if another app needs more memory than it will be given this memory. In that case the other app will be slower when you reopen it.

 

[Queen6]

I'm not missing that point, you simply fail to understand what PDF/PS is and how OS X memory management works nor do you seem to understand the basics of El Capitan (it's all about performance and stability).

What don't you get the performance is worse with the same data from a clean install, stop speaking rhetoric and consider that an issue at least for me is occurring, and possibly others.

Continuous stating people don't understand, in the face of issue is pointless. The performance is degrading with further interaction of the pdfs, this does not occur to the same level on my 10.10.5 systems. If it doesn't effect you, due to your usage and or workflow, no need to "chime in" as it`s not like you've offered any useful as advise other the "you don't understand" equally with two Mac`s in front of me it`s blatantly obvious...

Q-6

 

[dyn]

I hope you are not a police officer or a judge. The way you are pointing your finger at someone means that you end up putting innocent people in jail!

In your case it isn't Preview that is the problem but an upgrade gone wrong. Read back your own posts and count the amount of issues that you speak off. Again, the PDF thing is normal due to the PDF format and how memory management on a modern OS works. You need to stop blaming the wrong one and start looking at what is going on so you can start blaming the right one.

 

[Queen6]

I hope you are not a police officer or a judge. The way you are pointing your finger at someone means that you end up putting innocent people in jail!

In your case it isn't Preview that is the problem but an upgrade gone wrong. Read back your own posts and count the amount of issues that you speak off. Again, the PDF thing is normal due to the PDF format and how memory management on a modern OS works. You need to stop blaming the wrong one and start looking at what is going on so you can start blaming the right one.

Read my posts, initially I opted for the standard upgrade, to 10.11.0, subsequently due to issues predominantly with Apple`s Mail I did a full clean install of 10.11.0. The issue with Preview stands, if you can't get this fine, equally no need to respond. This technically may not be off issue to you, however it is to me and potentially others who require to deal with multiple pdf documents and other applications open at the same time.

Or simpler read before you respond, see #39 & #41. If you don't read what people write, it`s pointless responding as it`s nothing more than your opinion & rhetoric.

Q-8

 

[mag01]

I'm not missing that point, you simply fail to understand what PDF/PS is and how OS X memory management works nor do you seem to understand the basics of El Capitan (it's all about performance and stability). ...

You couldn't be more wrong and I'm not going to waste a lot of my time explaining why. But simply put:

- Preview at OS X 10.10.4 (or .5) takes considerably less RAM than at OS X 10.11.0 (or .1 Beta).
- While taking much more RAM at 10.11 it also performs worse (the difference might be marginal at higher end hardware,but at the MBA where I tested that it's pretty obvious) - where's that supposedly improved performance you're talking about? Nowhere to be seen. ;-)

- Adobe Reader (the current version DC 2015.009.2006) takes the same amount of RAM at both OS X 10.10 and 10.11. It also performs pretty much identically at both. Yes it's true that it takes more than Preview at 10.10 - 70MB for Preview at 10.10 vs. 285MB for Adobe Reader in both cases, but the results are at least consistent across both OS X versions (which hints that the problem with Preview at 10.11 lies elsewhere). On the other hand Preview at OS X 10.11 is totally beyond any reasonable RAM consumption while it doesn't deliver any improved performance at the same time, but actually the opposite.

You can't explain that with different memory management between OS X 10.10 and 10.11 since Adobe Reader doesn't exhibit anything similar at all - and I'm not even taking another applications into account which don't suffer from the same as well.

 

[Queen6]

You couldn't be more wrong and I'm not going to waste a lot of my time explaining why. But simply put:

- Preview at OS X 10.10.4 (or .5) takes considerably less RAM than at OS X 10.11.0 (or .1 Beta).
- While taking much more RAM at 10.11 it also performs worse (the difference might be marginal at higher end hardware,but at the MBA where I tested that it's pretty obvious) - where's that supposedly improved performance you're talking about? Nowhere to be seen. ;-)

- Adobe Reader (the current version DC 2015.009.2006) takes the same amount of RAM at both OS X 10.10 and 10.11. It also performs pretty much identically at both. Yes it's true that it takes more than Preview at 10.10 - 70MB for Preview at 10.10 vs. 285MB for Adobe Reader in both cases, but the results are at least consistent across both OS X versions (which hints that the problem with Preview at 10.11 lies elsewhere). On the other hand Preview at OS X 10.11 is totally beyond any reasonable RAM consumption while it doesn't deliver any improved performance at the same time, but actually the opposite.

You can't explain that with different memory management between OS X 10.10 and 10.11 since Adobe Reader doesn't exhibit anything similar at all - and I'm not even taking another applications into account which don't suffer from the same as well.

The only realistic solution is to feedback to Apple, Preview has been broken for some time now, nor is it clearly a priority to remedy. I will keep this Mac on 10.11 and see how it progresses, equally if nothing changes there is no way I can afford the system to be bogged down by something as simple as pdf`s. Field work prescribes Notebooks, not Workstations...

Q-6

 

[APlotdevice]

Screen savers are for laptops? I'd think quite the contrary. Those waste battery life. It's best to have your laptop go to sleep when idle.

 

[Queen6]

Screen savers are for laptops? I'd think quite the contrary. Those waste battery life. It's best to have your laptop go to sleep when idle.

Are you sure your on the right page?

Q-6

 

[APlotdevice]

Are you sure your on the right page?

Q-6

I'm responding to the OP.

 

[Queen6]

I'm responding to the OP.

Thx, got lost with all the other nonsense. Of all the posts, yours is the one of the few on track, pardon my intrusion 🙂

Q-6

 

[dyn]

You couldn't be more wrong and I'm not going to waste a lot of my time explaining why.

That would be because you simply can't as you clearly do not understand what is going on 😉 If you did you'd have explained why a vm running 10.11 with 2GB of memory has a far lower memory usage with Preview and the same PDF file as the iMac running 10.11 and 16GB of memory.

- Preview at OS X 10.10.4 (or .5) takes considerably less RAM than at OS X 10.11.0 (or .1 Beta).

And it also performance considerably less or have you forgotten all those complaints about Preview and PDF performance such as scrolling being really sluggish? Especially when the PDFs are more complex, have pictures in them, etc. etc. El Capitan fixes those problems as can clearly be seen in the release notes as well as the many reviews and experiences from people on the forums here and elsewhere (some of us check if issues we're having still exist in the new release). There have been some threads here specifically discussing this performance improvement (with a positive outcome).

- While taking much more RAM at 10.11 it also performs worse (the difference might be marginal at higher end hardware,but at the MBA where I tested that it's pretty obvious) - where's that supposedly improved performance you're talking about? Nowhere to be seen. ;-)

Where's that supposedly bad performance? Nowhere to be seen as can be seen in said reviews and experiences 😉 As I've explained my 2GB vm has a lower memory usage with Preview and bad performance compared to the 16GB iMac: memory usage is much higher and so is the performance. And so we are back at the PDF format being a PITA, that's why you need enough memory in order to have it perform well.

Just because it doesn't work well for you doesn't mean it doesn't work for the rest of the world or that it is broken!

- Adobe Reader (the current version DC 2015.009.2006) takes the same amount of RAM at both OS X 10.10 and 10.11.

Since when does Apple have access to the Adobe Reader source code? Since never so this is a really bad comparison. If Adobe didn't change anything about Adobe Readers memory usage than it'll behave the same way in 10.11 as it does in 10.10, 10.9 and whatever OS X version it supports. You should have checked what happens if the machine has 2GB, 4GB, 8GB, 16GB of memory plus the overall memory footprint compared to Preview. In both cases it is huge and it exhibits the same behaviour. Safari and other apps do exactly the same thing because that's how it works nowadays.

The two of you are like the OPs friends: ill-informed. Also, hijacking someones thread to complain about something isn't cool either, nor is this forum Apples bug tracking system. Good luck with getting your issues resolved (with such a mindset I doubt you'll ever be able to).

Screen savers are for laptops? I'd think quite the contrary. Those waste battery life. It's best to have your laptop go to sleep when idle.

When you sleep or hibernate the machine it will disconnect all devices and networking. If you are doing filetransfers and such in the background it is much better to use the screensaver because then all devices and networking are still available. If the machine is truly doing nothing then yes, it is better to have it sleep. A lot of people are not aware that you can't download anything in the background when you sleep/hibernate the machine. Screensavers are a good tool to prevent image burn in, that's their sole purpose but in OS X it is also used to lock the machine. That alone shows this isn't for laptops only but I can imagine the confusion due to OS X users using them to lock the machine.