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Is Iris Underpowered for Retina?

S

simpeeg

macrumors newbie
Original poster
Oct 12, 2010
8
0
So I bought this shiny new late 2013 15" 2.6 rMBP yesterday. I was suprised to see how Gmail felt sluggish (compared to my 2012 MBA). I booted Quartz Debug, and here's the (surprising?) results:

Scrolling in Gmail on 2012 13" 1.8 MBA: ~60 fps
Scrolling in Gmail on 2013 15" 2.6 rMBP: ~25 fps

Am I the only one around here thinking that the integrated graphics on the rMBP is way underpowered to drive the retina resolutions?

Don't get me wrong, I really love the high DPI of that panel. But I don't think that high density polish should come with a framerate cost.

I have become accustomed to the responsiveness an fluidity of my old MBA. I was at least expecting the same UI performance from a $3k-ish pro-grade laptop.

I really dig the overall performance of this machine: the SSD is blazing, the quad core chip plows through everything and the IPS panel is beautiful. The underpowered graphics chip is the ONLY flaw I have found so far with this laptop, but it's a deal breaker.

Maybe the Retina resolutions have arrived too early, and the industry should wait for the integrated graphics to be powerful enough to drive those panels at a consistent 60 fps, what do you think?
 
That's odd because others have reported smooth scrolling on the new 15" model. Have you compared the scrolling on the Iris Pro to the scrolling on the 750m? You can force your MacBook to run on the 750m all the time by disabling auto switching in the energy preferences.
 
It's software and how it handles Retina, not really hardware.

There's a smoother experience going from ML to Mavericks on my HD4000 Early 2013 Retina 15". But also, very little difference scrolling with the HD4000 vs the GT650M.
 
Hypathia said:
That's odd because others have reported smooth scrolling on the new 15" model. Have you compared the scrolling on the Iris Pro to the scrolling on the 750m? You can force your MacBook to run on the 750m all the time by disabling auto switching in the energy preferences.
Click to expand...

Yes I have tried, but the framerates did not appear to improve right away.

That is a non-solution IMO, because it defeats the purpose of having integrated graphics and will obviously drain the battery a lot faster. I don't want to go that way, and I think the framerates should be smooth even when running on Iris only.

Think of those 13" rMBP who owners don't have a dGPU to rely on :S I suspect they would experience similar issues.

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Jinzen said:
It's software and how it handles Retina, not really hardware.

There's a smoother experience going from ML to Mavericks on my HD4000 Early 2013 Retina 15". But also, very little difference scrolling with the HD4000 vs the GT650M.
Click to expand...

How can you be 100% sure this is not a hardware limitation? I'd be really happy to hear this will be fixed by a simple OS update, but my hopes are not too high :(
 
simpeeg said:
That is a non-solution IMO, because it defeats the purpose of having integrated graphics and will obviously drain the battery a lot faster. I don't want to go that way, and I think the framerates should be smooth even when running on Iris only.
Click to expand...

Sure, I just wanted to isolate the GPU as a possible factor. If your framerate doesn't improve on the 750m, then maybe your issue has nothing to do with the Iris Pro but with Safari? Do you run the same version of Safari on both MacBooks? They changed the way Safari renders scrollable areas. It now renders parts of the overlap in advance instead of rendering them only when they become visible. Maybe that combined with Gmail triggers a bug? Do you have the same issue on other websites or in other applications?
 
Hypathia said:
Sure, I just wanted to isolate the GPU as a possible factor. If your framerate doesn't improve on the 750m, then maybe your issue has nothing to do with the Iris Pro but with Safari? Do you run the same version of Safari on both MacBooks? They changed the way Safari renders scrollable areas. It now renders parts of the overlap in advance instead of rendering them only when they become visible. Maybe that combined with Gmail triggers a bug? Do you have the same issue on other websites or in other applications?
Click to expand...

This issue happens both in Safari and Chrome. Other websites seem more responsive (in general), but my old MBA always seems more fluid (independently of the application or website)
 
simpeeg said:
Yes I have tried, but the framerates did not appear to improve right away.

That is a non-solution IMO, because it defeats the purpose of having integrated graphics and will obviously drain the battery a lot faster. I don't want to go that way, and I think the framerates should be smooth even when running on Iris only.

Think of those 13" rMBP who owners don't have a dGPU to rely on :S I suspect they would experience similar issues.

----------



How can you be 100% sure this is not a hardware limitation? I'd be really happy to hear this will be fixed by a simple OS update, but my hopes are not too high :(
Click to expand...

Well, my early 2013 Retina 15 scrolls at the same FPS on TheVerge.com regardless of whether I force it on the HD4000 or the GT 650M.

The scrolling is much smoother on Mavericks than ML, but still isn't iOS smooth.
 
I'm not sure, but the scrolling in gmail is not native I mean it appears to be driven by javascript/HTML instead, it occurs inside a HTML element (maybe a div), not directly into the web browser that means that it may not be as fast as a native app, it all depends on the web browser.
 
The same "issue" exists on last gen MBPs. It is a software issue.

http://nightly.webkit.org/

there you can download the nightly version of safari (assuming that's the browser you are using) that will make you scroll smoothly.

Edit - i wouldnt use a beta version of a browser as my day to day. Just a caution.
 
If it were a software issue, I believe Apple would have fixed it already. Retina screens have been out for more than a year, and those framerate issues have never been resolved.
 
Just a note, it's not actually a GPU performance cap issue. The performance problems that can arise with retina resolutions are a result of maxing out a core of the CPU performing the scaling and other pre-rendering operations before the final frame is produced by the GPU.

The GPUs in any of these machines are more than sufficiently fast to draw text and 2D images on a screen at retina resolutions. Mavericks has improved performance because the pre-rendering work has been optimized and as much of it as possible is now exported to the GPU, however there's still plenty of room for improvement.

Unfortunately just throwing a faster GPU at the problem won't have any impact. Faster CPUs could help, but that's an inefficient solution to an optimization problem.

Laptops handling these kinds of resolutions is still a very new thing; it wasn't long ago that it was a big deal for a desktop machine to properly drive a 2560x1440 display, and now we have laptops running 2880x1800 on their internal displays.

Honestly this is the reason I hope Apple's switch to IGZO next year doesn't come with more pixels; It's already a strain on the system at this resolution and most people who aren't 20 would need convex lenses to even see the difference.
 
Scrolling in Safari is quite smooth in the vast majority of cases, even on my 2012 base model 13" rMBP. The whole "UI lag" is generally not an issue except in cases where the software has not been optimized (for example MS Office for Mac is horrible in terms of lag).

The UI animations such as minimizing, maximizing, full screen switching, and Mission Control are also smooth in "best for retina" mode and the 1440x900 scaled mode; however the 1680x1050 scaled mode got considerably worse after upgrading to Mavericks for some reason.


Anyway the HD4000 has no problem driving the retina screen, so neither should the Iris. Any software that isn't well optimized for retina displays is going to lag on your system regardless of the GPU.
 
I went to gmail on Safari opened the Web Inspector and found what I suspected: the scrolling occurs inside a HTML element: a huge <div> element tag to be accurate, this element has a lots of objects inside, so scrolling may suffer some lag, the rest of the scrolls in Mavericks are lightning fast including mission control in my case, this is the only case I've found that has little lag, this can be optimised further, the hardware is fully capable to render the retina screen.

I wouldn't blame the browser neither Mavericks, maybe the webkit needs some tweaks here and there...
 
Last edited:
Weird, I've got the high end 13" (similar resolution, worse GPU, worse CPU) and it's not sluggish at all in gmail.

I've also got the high end 15" sitting right next to it - I can't tell the difference between either - unless I load up a graphic intensive game or benchmark. Obviously the 15" has the 750m, so it's going to be the better performer, but outside of games I can't tell a lick of difference. Especially in something trivial like gmail.
 
Yep, gmail seems to be a weird case. Also getting 25-30 fps here with the 2012 rMBP. Facebook and the Verge are steady 50-60 fps. My iMac (780M) manages 60 fps with gmail.
 
simpeeg said:
If it were a software issue, I believe Apple would have fixed it already. Retina screens have been out for more than a year, and those framerate issues have never been resolved.
Click to expand...

Um, Apple has notoriously poor performing graphics drivers. Bugs take ages to fix or are never fixed and everything is several revisions behind Windows / Linux. Apple do not put resources into the GPU drivers, they are merely good enough. Professionals have been asking for 10bit output support for years, and some developers have actually written kernel drivers to enable it but Apple have never tooled up to do this. The hardware is technically far more than capable of driving the display at the required framerates.
 
Atomic Walrus said:
Just a note, it's not actually a GPU performance cap issue. The performance problems that can arise with retina resolutions are a result of maxing out a core of the CPU performing the scaling and other pre-rendering operations before the final frame is produced by the GPU.
Click to expand...

The scaling is performed on the GPU. Everything else would be beyond silly.

Atomic Walrus said:
Mavericks has improved performance because the pre-rendering work has been optimized and as much of it as possible is now exported to the GPU, however there's still plenty of room for improvement.
Click to expand...

Mavericks has improved scrolling performance mainly because it is rendering scrollable UI elements on background threads.

Atomic Walrus said:
Laptops handling these kinds of resolutions is still a very new thing; it wasn't long ago that it was a big deal for a desktop machine to properly drive a 2560x1440 display, and now we have laptops running 2880x1800 on their internal displays.
Click to expand...

Matrox Parnelia back in 2002 didn't have any problem with two 2048 x 1536 displays at the same time. The reason why driving a high-res display was a big deal is that such displays only recently became available to general consumer public. So GPU vendors wouldn't even bother with high resolutions. The performance to do compositing window manager on high-res surfaces has been there for years (not necessarily with iGPUs, true).
 
simpeeg said:
So I bought this shiny new late 2013 15" 2.6 rMBP yesterday. I was suprised to see how Gmail felt sluggish (compared to my 2012 MBA). I booted Quartz Debug, and here's the (surprising?) results:

Scrolling in Gmail on 2012 13" 1.8 MBA: ~60 fps
Scrolling in Gmail on 2013 15" 2.6 rMBP: ~25 fps

...
Click to expand...

Could you post instructions how we can check the framerate?
 
I found the same issue on the 15". Try Chrome Canary, it's incredibly smooth. Gmail scrolls like a dream now :)
 
NO, the iris pro is not too slow, if i can get 47fps on csgo at 2880x1800 with all settings max, then the gpu is definitely powerful enough to scroll a web page

your problem is going to be the browser not using the gpu properly for rendering / composting

if you are using chrome go to chrome://flags and enable the gpu acceleration features and accelerated overflow scroll (or try a dev / canary version)
 
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