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2018 MBP 13"- Slow with an external monitor

Rigtee

macrumors member
Original poster
Sep 19, 2018
65
28
Belgium
Hello everyone,

I've owned a 2018 MBP 13" (quad-core CPU-i5 2.3GHz, 16GB RAM) for about a year and recently I bought a 32" 4K external monitor (BenQ EW3270U) to work more comfortably with it while at home.

With the Thunderbolt 3 USB-C port, I was expecting the machine to be pretty fast (the cable from the screen is directly plugged into the laptop) and although it is the case for *very* simple tasks (web browsing, listening to music, typing documents), it is definitely slowing down when I'm asking for more. Lightroom editing for instance is really a pain in the arse: somewhat smooth when used on the Mac directly but sluggish when connected in clamshell mode to the screen. Same story when viewing a video on YT, the fullscreen on/off animations are not smooth. I'm using the scaled resolution of 2560x1440 (in 1080p, true "retina" mode, the text was too big for my liking and in native resolution it is illegible).

Of course I'm being picky here. It does perform well most of the time. But isn't it legitimate to complain about the lack of smoothness when I'm doing "pro" work? Isn't such a modern €2500 machine supposed to handle everything you throw at it perfectly?

Might a dedicated GPU be useful for that kind of scenario?

Thanks!
 
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cynics

macrumors G4
Jan 8, 2012
11,630
1,907
I have the same Mac as you except 8gb RAM.

Your GPU is lacking for that workload. The UI uses hardware acceleration so its really fast and fluid. If the GPU is being heavily used by another program you'll get UI stutter and lag. You can see this for yourself if you stop most foreground processes, open activity monitor and goto the menu bar, Window > GPU History and then start swiping the UI around. You'll see the spikes in the graph fr.

Keep in mind that your monitor is capable of requiring a lot of system resources at the drop of a hat. For comparison a 1080p 60hz 8bit monitor requires bandwidth of 4-5Gbps.. That BenQ monitor is 4k 60hz 10bit which can exceed 20Gbps. And that is just the bandwidth requirements, that data still needs to be processed.

Using a scaled resolution isn't helping with performance either.

Plus you have 1.5gb of VRAM for a piece of software (Lightroom) that has a minimum requirement of 2gb of VRAM when used with a 4-5k monitor but they recommend 4gb of VRAM. Personally I always consider the recommended spec as being the minimum spec and I'll try to exceed it a bit. You are below the minimum....

I don't feel the lack of UI smoothness is a legitimate complaint under these specific conditions. Regardless of any computers specs or how "Pro" it is you can find a way to bottleneck performance.

To illustrate my point above this is just playing a 4k60hz HDR video from YouTube (FireFox browser) on an external 4k60hz HDR display from my MacBook via USB cable (no hub).

Screen Shot 2019-09-07 at 11.04.43 PM.png


CPU usage is so high because the video was encoded with VP9 (if it was HEVC I doubt it would have played very smooth). Since the video was buffering the CPU usage and temps were dropping off toward the end. Prior to that CPU temps were around 90c with the fans at max. And it was throttling on power consumption limits. Just to play a video....Maintained a nice all core turbo the entire time though....
 
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Rigtee

macrumors member
Original poster
Sep 19, 2018
65
28
Belgium
I have the same Mac as you except 8gb RAM.

Your GPU is lacking for that workload. The UI uses hardware acceleration so its really fast and fluid. If the GPU is being heavily used by another program you'll get UI stutter and lag. You can see this for yourself if you stop most foreground processes, open activity monitor and goto the menu bar, Window > GPU History and then start swiping the UI around. You'll see the spikes in the graph fr.

Keep in mind that your monitor is capable of requiring a lot of system resources at the drop of a hat. For comparison a 1080p 60hz 8bit monitor requires bandwidth of 4-5Gbps.. That BenQ monitor is 4k 60hz 10bit which can exceed 20Gbps. And that is just the bandwidth requirements, that data still needs to be processed.

Using a scaled resolution isn't helping with performance either.

Plus you have 1.5gb of VRAM for a piece of software (Lightroom) that has a minimum requirement of 2gb of VRAM when used with a 4-5k monitor but they recommend 4gb of VRAM. Personally I always consider the recommended spec as being the minimum spec and I'll try to exceed it a bit. You are below the minimum....

I don't feel the lack of UI smoothness is a legitimate complaint under these specific conditions. Regardless of any computers specs or how "Pro" it is you can find a way to bottleneck performance.

To illustrate my point above this is just playing a 4k60hz HDR video from YouTube (FireFox browser) on an external 4k60hz HDR display from my MacBook via USB cable (no hub).

View attachment 856608

CPU usage is so high because the video was encoded with VP9 (if it was HEVC I doubt it would have played very smooth). Since the video was buffering the CPU usage and temps were dropping off toward the end. Prior to that CPU temps were around 90c with the fans at max. And it was throttling on power consumption limits. Just to play a video....Maintained a nice all core turbo the entire time though....

Thanks a lot for your thorough and in-depth answer!

I did not think the GPU might bottleneck the performance here but it seems logical after all, having integrated graphics while driving a 4K monitor and doing some Lightroom work (which is not known as the most-optimised piece of software on MacOS) does not maximising the chances to perform well.

Anyway, I might then accept the reality as it is and move on. Actually I sold one year ago my 2016 15" MBP for keyboard reliability issues and now kinda regret it when I'm doing some video/photo editing. Buying an eGPU is not the best option for me as it is expensive and not that minimalist. I might then look for a 2019 15" MBP if such a problem repeats itself in the future...or simply wait for the 16" MBP everyone is talking about ;)
 
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cynics

macrumors G4
Jan 8, 2012
11,630
1,907
Thanks a lot for your thorough and in-depth answer!

I did not think the GPU might bottleneck the performance here but it seems logical after all, having integrated graphics while driving a 4K monitor and doing some Lightroom work (which is not known as the most-optimised piece of software on MacOS) does not maximising the chances to perform well.

Anyway, I might then accept the reality as it is and move on. Actually I sold one year ago my 2016 15" MBP for keyboard reliability issues and now kinda regret it when I'm doing some video/photo editing. Buying an eGPU is not the best option for me as it is expensive and not that minimalist. I might then look for a 2019 15" MBP if such a problem repeats itself in the future...or simply wait for the 16" MBP everyone is talking about ;)

I tend to agree, I'm not a huge fan of an eGPU because my workload doesn't warrant one. However if it did it could be an invaluable addition.

Something of note about a dedicated GPU (internal or external) is the biggest gain to performance when it comes to productivity (video editing, photo editing, etc) is just having dedicate graphics. The card itself doesn't matter as the initial gain is moving the load off the CPU to free it up for CPU task. The specific GPU used will show performance gains depending on the actually task and its requirements.

You really wouldn't need to break the bank for Lightroom.

An eGPU is upgradable down the road once you have the case so you keep a minimalist laptop and just plug into the eGPU.

An eGPU doesn't need to be front and center on your desk. I keep all my peripherals on a shelf I built under my desk so there is only one USB C cable that plugs into the laptop on the desk, under the desk it breaks out for the external display, ethernet, etc etc...

Just food for thought...
 
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Fishrrman

macrumors Core
Feb 20, 2009
20,860
7,464
OP wrote:
"I'm using the scaled resolution of 2560x1440 (in 1080p, true "retina" mode, the text was too big for my liking and in native resolution it is illegible)."

THERE'S your problem.

It takes a lot more "computing horsepower" to run a 4k display in scaled mode than in native mode (either full 4k or HiDPI). This is slowing down the MacBook Pro.

You have three choices that I see:
1. Set the display for 4k HiDPI mode (looks like 1080p)
or
2. Get a 27" 4k display and run THAT in 4k HiDPI mode (looks like 1080p but the text will be smaller)
or
3. Get a 32" NON-4k display. That will run in native 1440p mode and will be easy for the MBP to handle.

The MBP will run much better with ANY of the above solutions.
 
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Rigtee

macrumors member
Original poster
Sep 19, 2018
65
28
Belgium
I tend to agree, I'm not a huge fan of an eGPU because my workload doesn't warrant one. However if it did it could be an invaluable addition.

Something of note about a dedicated GPU (internal or external) is the biggest gain to performance when it comes to productivity (video editing, photo editing, etc) is just having dedicate graphics. The card itself doesn't matter as the initial gain is moving the load off the CPU to free it up for CPU task. The specific GPU used will show performance gains depending on the actually task and its requirements.

You really wouldn't need to break the bank for Lightroom.

An eGPU is upgradable down the road once you have the case so you keep a minimalist laptop and just plug into the eGPU.

An eGPU doesn't need to be front and center on your desk. I keep all my peripherals on a shelf I built under my desk so there is only one USB C cable that plugs into the laptop on the desk, under the desk it breaks out for the external display, ethernet, etc etc...

Just food for thought...

True, but then comes the question: should I do “serious work” like Lightroom or Final Cut on the go? If yes, then I might switch back to a 15”.

I think I’ll hold to my 13” for the upcoming months and, instead of telling myself that I need that extra power, see if I encounter cases where I wish I had a dGPU. Then it’ll time to switch or to buy an eGPU.
[doublepost=1568727485][/doublepost]
OP wrote:
"I'm using the scaled resolution of 2560x1440 (in 1080p, true "retina" mode, the text was too big for my liking and in native resolution it is illegible)."

THERE'S your problem.

It takes a lot more "computing horsepower" to run a 4k display in scaled mode than in native mode (either full 4k or HiDPI). This is slowing down the MacBook Pro.

You have three choices that I see:
1. Set the display for 4k HiDPI mode (looks like 1080p)
or
2. Get a 27" 4k display and run THAT in 4k HiDPI mode (looks like 1080p but the text will be smaller)
or
3. Get a 32" NON-4k display. That will run in native 1440p mode and will be easy for the MBP to handle.

The MBP will run much better with ANY of the above solutions.

Is the scaled resolution affecting my performance that much? I’ll try to do the same task (editing photos in LR) using the HiDPI mode of 1080p, looks a bit big but I’ll get used to it. 4K native is not an option for me, have good eyes but uncomfortable.

I actually bought that screen of that size to play some games as well, that’s why it’s not the “ideal screen and resolution ratio” for a Mac.
 
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imp3rator

macrumors 6502
Dec 25, 2019
398
279
Hello. This is an old thread, but did you solve this ? Did you upgrade macbook or changed the monitor ?
 
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Rigtee

macrumors member
Original poster
Sep 19, 2018
65
28
Belgium
Hello. This is an old thread, but did you solve this ? Did you upgrade macbook or changed the monitor ?
Hi! Thanks for your answer, always good to get some activity from old threads ;)

I could say that I "partially" solved the issue, let me explain. I didn't resell my 2018 MBP, it is still the machine I'm typing on at the moment (or more precisely, I have it connected to another monitor). Indeed, I even bought, in addition to the first BenQ EW3270, another monitor which is more precise in the colour fidelity (and somehow more demanding, I notice a very slight performance degradation compared to the EW): it is the BenQ PD3220U, also 4K and connected via Thunderbolt 3 to my MBP. I am really happy with those two monitors but don't use them at the same time, I have them in different places.

Coming back to the laptop issue, I can say that it is 95% perfect. As it was recommended by some in this thread, I'm using a scaled resolution but a "perfect" scaled one. It is actually the first one "looks like 1920 x 1080". It is important to avoid the 3 options in the middle as those are not perfect scaled and may degrade performance. I was not used to the bigger text first but it is really comfortable and not that big after all, I can still see a lot of content on my screen:



1610980122574.png


Performance has been stable with Catalina and now Big Sur with no issue for day-to-day use: browsing, email, messaging, light office tasks (Excel, Word, PowerPoint). Last year, I even managed to work on a FCPX video and an Affinity Design catalog. Interface was mostly smooth but the laptop can get quite noisy, especially with the open lid and the webcam turned on (like during a MS Teams call, very frequent with the current pandemic). Another issue that I sometimes encountered (on my uni platform, Moodle) is scaling: text can be really big on the screen when accessing a webpage, almost like I accidentally clicked on the zoom button of Safari (200%). I have to scale it back every time, that is cumbersome.

However, when taking my laptop with me, I am always surprised by how small it is 😂 I guess that is part of the comfort you gain from an external screen. I was planning to acquire the new M1 Mac Mini to test the new chip but also to run it as a home server and to get a proper desktop. I will make a post if that happens but for now, it is fine. What I wish was maybe more GPU power (to handle things like video editing), I guess I'll be satisfied with the next M1 14/16" MBP! My 2018 MBP is thus still a capable machine!
 

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j_in_tx

macrumors member
Jun 28, 2018
38
29
Thanks a lot for your thorough and in-depth answer!

I did not think the GPU might bottleneck the performance here but it seems logical after all, having integrated graphics while driving a 4K monitor and doing some Lightroom work (which is not known as the most-optimised piece of software on MacOS) does not maximising the chances to perform well.

Anyway, I might then accept the reality as it is and move on. Actually I sold one year ago my 2016 15" MBP for keyboard reliability issues and now kinda regret it when I'm doing some video/photo editing. Buying an eGPU is not the best option for me as it is expensive and not that minimalist. I might then look for a 2019 15" MBP if such a problem repeats itself in the future...or simply wait for the 16" MBP everyone is talking about ;)
It should be smooth for more than just simple tasks. My 2018 15” i7 was having issues playing 4k videos on Youtube with nothing else running (after complete reformat/re-install). I called Apple and they let me send it in (I have applecare). They sent it back with a Logic board replacement. And viola! It works great just as anyone would expect it to. I ran the 4k Youtube, parallels, many safari tabs, etc... and it’s smooth even under decent load. Before, I wouldn’t be able to do anything....NOTHING. It was very frustrating. I lost $1300 on this issue. I bought a new 2019 16” because the 2018 was unacceptable.

I became/still unemployed several months ago and decided to look into the 2018 problem. Anyway, it’s fixed now, I sold the 2019 on Swappa for a $1300 loss (8 months of home usage). I’m planning to sell the 2018 soon and will get an M1 Air. I just wish parallels would already have something ready for the M1.
 
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imp3rator

macrumors 6502
Dec 25, 2019
398
279
Thanks for the reply !

I tried several tests but with less powerfull machine - Air 2020 i3 - dual core - 1.1. Ghz

It works with 1080p retina mode quite good. But with FullHD monitor it was twice as fast in higher loads (pushing 2M pixels vs 8M). 2560x1440 was laggy because it renders in 5K (15M pixels) and then downsample to 4K (8M pixels) and it is not "integer" scaled resolution.

But - when I connect USB-C to DP cable - temperature is in idle 10 C higher (65 C vs 55 C)
I find several youtube videos where is problem with 2020 Macbook Pro - because new intel chip (ice lake) include thunderbolt controller in package which increase temperature when handle 4K output (but it is faster for external SSD or eGPU)
2019, 2018 models etc have TB controller somewhere in motherboard so they works better (less heat - less fan noise) than 2020 models.

Obviously M1 Macs solved it with higher performance chip, lower nm process, less heat and own architecture.
 
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