Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Why does MacOS slow down terribly when switching to 3008x1692 resolution on an external display?

radlfuchs

radlfuchs

macrumors newbie
Original poster
Jan 26, 2018
11
6
Munich, Germany
Hi MacRumors,

I have the following setup:
  • MacBook Pro 15“ (Mid 2014)
  • Dell UP3216Q 4k Display connected via Mini DisplayPort
  • MacOS High Sierra

Following observations:
  • The display works just fine on the resolution the MacOS detects as standard (3840x2160)
  • But on this resolution all UI elements and font sizes are way too small, for me changing font sizes in every app is not an option (one reason for this is that some menus will still have tiny fonts)
  • MacOS allows me to switch to scaled resolutions, for me the perfect one is 3008x1692
  • Once I switch to this resolution, the whole system feels terribly slow (MacOS even prints out a warning that this might happen due to the scaling)
  • A colleague of mine has the same screen on a MacBook Pro 13“ (Late 2017), MacOS also feels quite slow when he switches to this resolution (maybe a little less slow)
  • This is why I think that it is not as easy to say that my machine is just too old
  • It is quite hard to find out if there is a chance to drive this display on 3008x1692 without performance issues
  • I read some threads that with MacOS High Sierra sort-of discontinued so-called HiDPI resolutions, but I did not fully grasp what that means; e.g. does Apple have to actively support a certain screen?)

What I tried:
  • CPU load seems fine on 3008x1692
  • GPU load is not as easy to check, but I can say at least that the MacOS seems to use the dedicated graphics card
  • I installed the tool Resolutionator, which allows quick switching to other resolutions
  • This tool also allows me to switch to 3008x1692, but this resolution is marked as „non-retina“
  • When I do this, then MacOS feels normal again, but the image is a bit blurry
  • The only difference between the two (configured by MacOS settings vs. configured by Resolutionator) is the sharpness of the image, on both resolutions I can see the same "usable space"

My questions:
  • What is the difference between setting 3008x1692 in MacOS settings (image fine, feels like 4k) and setting it in external tools like Resolutionator (image blurry)?
  • Does anyone know how to fix this or should I return the screen?
(My opinion: MacOS seems to "optimize" the image so that it looks crisp. For scaled resolutions this maybe is too GPU-intense to keep a smooth performance. But this would in other words mean, that the other resolution configured by Resolutionator is just plain 3008x1692 without any optimizations - but why is this image blurry?)


Thanks in advance and best regards!
 
Last edited:
Yes like you say macOS sharpens the image and this increases data quantity so reduces performance, the Resonator blurry image is less data-intensive so runs more smoothly. No way around it with a laptop and fixed components, you are seeing the capacity limit of your hardware.
 
Last edited:
vkd said:
Yes like you say macOS sharpens the image and this increases data quantity so reduces performance, the Resonator blurry image is less data-intensive so runs more smoothly. No way around it with a laptop and fixed components, you are seeing the capacity limit of your hardware.
Click to expand...

Thanks, vkd.

So if the Apple sharpening-magic is left out, the performance goes up. This makes sense to me. :)

What makes less sense is how blurry the plain-3008x1692-image looks like. :(
 
  • Like
Reactions: vkd
radlfuchs said:
Hi MacRumors,

I have the following setup:
  • MacBook Pro 15“ (Mid 2014)
  • Dell UP3216Q 4k Display connected via Mini DisplayPort
  • MacOS High Sierra

Following observations:
  • The display works just fine on the resolution the MacOS detects as standard (3840x2160)
  • But on this resolution all UI elements and font sizes are way too small, for me changing font sizes in every app is not an option (one reason for this is that some menus will still have tiny fonts)
  • MacOS allows me to switch to scaled resolutions, for me the perfect one is 3008x1692
  • Once I switch to this resolution, the whole system feels terribly slow (MacOS even prints out a warning that this might happen due to the scaling)
  • A colleague of mine has the same screen on a MacBook Pro 13“ (Late 2017), MacOS also feels quite slow when he switches to this resolution (maybe a little less slow)
  • This is why I think that it is not as easy to say that my machine is just too old
  • It is quite hard to find out if there is a chance to drive this display on 3008x1692 without performance issues
  • I read some threads that with MacOS High Sierra sort-of discontinued so-called HiDPI resolutions, but I did not fully grasp what that means; e.g. does Apple have to actively support a certain screen?)

What I tried:
  • CPU load seems fine on 3008x1692
  • GPU load is not as easy to check, but I can say at least that the MacOS seems to use the dedicated graphics card
  • I installed the tool Resolutionator, which allows quick switching to other resolutions
  • This tool also allows me to switch to 3008x1692, but this resolution is marked as „non-retina“
  • When I do this, then MacOS feels normal again, but the image is a bit blurry
  • The only difference between the two (configured by MacOS settings vs. configured by Resolutionator) is the sharpness of the image, on both resolutions I can see the same "usable space"

My questions:
  • What is the difference between setting 3008x1692 in MacOS settings (image fine, feels like 4k) and setting it in external tools like Resolutionator (image blurry)?
  • Does anyone know how to fix this or should I return the screen?
(My opinion: MacOS seems to "optimize" the image so that it looks crisp. For scaled resolutions this maybe is too GPU-intense to keep a smooth performance. But this would in other words mean, that the other resolution configured by Resolutionator is just plain 3008x1692 without any optimizations - but why is this image blurry?)


Thanks in advance and best regards!
Click to expand...

Retina is basically the Apple terms of HiDPI.

In your case, when you choose 3008x1692 in system preference. The GPU actually rendering everything at higher resolution and then scale it down.

A simple test can tell you what's the resolution your GPU need to handle.

1) choose 3008x1692 in system preference (the one that with Retina)
2) Press "Command + Shift + 3" at the same time
3) There should be a screen capture on your desktop
4) left click on the image, and then press "Command + I"
5) Now, check the dimension as per screen capture
Screen Shot 2018-01-26 at 23.46.20.jpg

In my case, it's rendering at 7680x2160, and then scale down to 3840x1080 HiDPI (or Retina). If you choose 3008x1692 Retina, your GPU may require to render at 6016x3383, which is way beyond 3840x2160. This may be the reason why causing the lag.

In this case, choose 1440P Retina or even lower resolution may help. But of course, you will have less desktop space to use. Unless you really running out of space, usually using lower resolution but with HiDPI will make your eyes much more comfortable.
 
Last edited:
h9826790 said:
Retina is basically the Apple terms of HiDPI.

In your case, when you choose 3008x1692 in system preference. The GPU actually rendering everything at at higher resolution and then scale it down.

A simple test can tell you what's the resolution your GPU need to handle.

1) choose 3008x1692 in system preference (the one that with Retina)
2) Press "Command + Shift + 3" at the same time
3) There should be a screen capture on your desktop
4) left click on the image, and then press "Command + I"
5) Now, check the dimension as per screen captureView attachment 748626
In my case, it's rendering at 7680x2160, and then scale down to 3840x1080 HiDPI (or Retina). If you choose 3008x1692 Retina, your GPU may require to render at 6016x3383, which is way beyond 3840x2160. This may be the reason why causing the lag.

In this case, choose 1440P Retina or even lower resolution may help. But of course, you will have less desktop space to use. Unless you really running out of space, usually using lower resolution but with HiDPI will make your eyes much more comfortable.
Click to expand...

Thank you for the detailed answer. I can confirm the following:

1) 3008x1692 configured as non-retina via additional tool leads to a screenshot size of 3008x1692

2) 3008x1692 configured via MacOS (Retina / HiDPI) leads to a screenshot size of 6016 × 3384

3) 2560×1440 configured via MacOS (Retina / HiDPI) leads to a screenshot size of 5120 × 2880

So the MacOS setting is more like "available screen space equivalent to x*y resolution".

Rendering in 6016 × 3384 and scaling down to 3008x1692 seems too much to handle for the hardware.

I will check if 2560×1440 (Retina / HiDPI) works for me. It seems less laggy compared to the higher-res-options, but I guess the lags will soon start to annoy me too much.

The question then will be if I can live with the blurry image on a > 1000 USD screen running on a < 3 year old MacBook Pro (WTF!).

What troubles me is that even current Apple hardware, like the mentioned MacBook 13" from my colleague, seems to have almost the same issues.
 
  • Like
Reactions: legato01 and h9826790
OP:

The specs in your original post list the display as being "4k" with a native resolution of 3840x2160.

Seems to me that the MBP is going to run best if you set it up as a "retina type" resolution, i.e., "HiDPI mode".

Any other resolution is probably going to overtax the GPU/CPU and that's why things are slowing down on you.

Here's a page you need to read carefully:
https://support.apple.com/en-us/HT206587

Looks like a 2014 MBPro 15" can do 4k in HiDPI mode with the proper connections...
 
Fishrrman said:
OP:

The specs in your original post list the display as being "4k" with a native resolution of 3840x2160.

Seems to me that the MBP is going to run best if you set it up as a "retina type" resolution, i.e., "HiDPI mode".

Any other resolution is probably going to overtax the GPU/CPU and that's why things are slowing down on you.

Here's a page you need to read carefully:
https://support.apple.com/en-us/HT206587

Looks like a 2014 MBPro 15" can do 4k in HiDPI mode with the proper connections...
Click to expand...

OK, I will have a look on the link.

I have seen screenshots from the MacOS settings widget when clicking on the "scaled" option while the alt-key is pressed.

These screenshots put "HiDPI" after some resolutions, like here (not taken from my screen) ...

hidpi-mode-system-preferences.png


... but this is not the case for me. I don't know if this makes a difference.

On the other hand, on my machine I can select a checkbox if "low resolution options" should be shown as well ... this may implicitly mean that all others are HiDPI / Retina.
 
radlfuchs said:
OK, I will have a look on the link.

I have seen screenshots from the MacOS settings widget when clicking on the "scaled" option while the alt-key is pressed.

These screenshots put "HiDPI" after some resolutions, like here (not taken from my screen) ...

hidpi-mode-system-preferences.png


... but this is not the case for me. I don't know if this makes a difference.
Click to expand...

That depends on the config and OS version. With a newer system, you may not see "HiDPI" anymore, but "low resolution" for non HiDPI options.
Screen Shot 2018-01-27 at 01.29.26.jpg
 
Fishrrman said:
Another important factor:
Are you using the right cable?
Click to expand...

This should not slow down the Mac, either work or doesn't work.

Since OP mentioned he can get 3840x2160 smoothly (and detected by the OS natively). It seems he has the right cable for this 4K display.
 
Hes using a non native resolution a not normal scaled resolution on a three year old mobile computer that's already pushing the better part of 4K on his laptop screen, I'd be surprised if it didn't drag.
 
  • Like
Reactions: strawbale
Thanks everybody!

What I was trying to get:
* Retina image quality
* Reasonable trade off between usable screen space and UI element size
* No reduction of system performance because of the external screen

It seems like this is not possible with my hardware setup.

I either need to become ant man in order to get comfortable with 3840x2160 or get other hardware.

So I guess I will go back to using my two Full-HD 24" screens instead, no performance problems there
 
Last edited:
I have method with Google Photos web site. With integrated graphics I can scroll and open/close photos with fluid animations. With GeForce card in use na macOS 10.13+ its very slow and not fluid.
I was at Apple Store with this problem and support almost laught at me, and said, that I need to wait for fix, or downgrade to Sierra.
 
OK, thanks for the info.

Small update from my side. I installed iStat Pro to get some info on the GPU/VRAM usage. When switching to e.g. 3008x1692 (Retina), the VRAM Usage is at its maximum.

In contrary, a freshly booted system shows only about 70% VRAM usage, so I tried to track down at what point the VRAM usage reaches maximum.

It looks like that the main problem for the lag comes from one application that I have open on my machine all the time (IntelliJ, a Java-based software developer tool).

Knowing all this I googled explicitly for this problem and found a recommendation to install the MacOS drivers from Nvidia, so I did this.

This was a first time experience on Mac for me: Installing a graphics driver! It almost felt like the bad old Windows days. But it looks like the lags occur less now.

In iStat Pro the NVRAM usage also went down. I will keep an eye on this as I am not totally convinced yet. But there may be hope, again.
 
  • Like
Reactions: h9826790
Here's the scaling thing - macOS doesn't do scaling the way Windows does, i.e. it doesn't scale UI elements and fonts by a percentage. macOS uses either the native mode (screen estate = resolution) or HiDPI (screen estate = resolution/2, which means that a single "area" pixel is rendered by four (2x2) display pixels.

So for a 3840x2160 screen your options are to run it natively (with the screen estate of a 3840x2160 screen), which can result in everything being small and barely readable, or in HiDPI, with the screen estate of a normal FullHD screen (1920x1080) but rendered twice as sharp.

Besides that, there are other, in-between, options, but they are all implemented as "render the image on a virtual screen, then just scale and display the result" and will all look noticeably worse.

Unfortunately, that's the way macOS does it.
 
  • Like
Reactions: garbonsai and Gen0
It seems that Apple is not interested in true resolution independence. Unfortunately, since macOS does 100dpi well, or 200dpi in retina/HiDPI, but most new high resolution displays, like yours, are around 150, which brings all the issues you are seeing.
 
h9826790 said:
Yeah, and reduce motion as well (less motion for the users to see the lag :p)
Click to expand...
I had this problem in Sierra, just updated to Mojave hopping that it's gonna solve
3008X1692 is the best for any monitor around 27 to 32 inches

I have Smooth operation with HiDPI 3840X2160 or HiDPI 1920X1080
but everything in between (like 1440p or 1692p ,...) cause the problem in apps specially when they are full screen.

so my GPU can handle 2160p HiDPI very well, why it can't handle the lesser resolution?!

Screen Shot 2019-08-16 at 7.06.19 PM.png
 
MapleGreen said:
I had this problem in Sierra, just updated to Mojave hopping that it's gonna solve
3008X1692 is the best for any monitor around 27 to 32 inches

I have Smooth operation with HiDPI 3840X2160 or HiDPI 1920X1080
but everything in between (like 1440p or 1692p ,...) cause the problem in apps specially when they are full screen.

so my GPU can handle 2160p HiDPI very well, why it can't handle the lesser resolution?!

View attachment 853361
Click to expand...

HiDPI 3840x2160 means rendering at 7680x4320, you tried that setting?
 
in 2160p HiDPI I have no problem at all
and by looking too the text closely I can tell I am at HiDPI mode
I can't even select low resolution with 2160p or 1080p there isn't option for it!
but with other resolutions there are two options (Hi/Low)
in these resolutions I have problem !!

Screen Shot 2019-08-16 at 7.31.17 PM.png

Screen Shot 2019-08-16 at 7.38.01 PM.png
 
MapleGreen said:
in 2160p HiDPI I have no problem at all
and by looking too the text closely I can tell I am at HiDPI mode
I can't even select low resolution with 2160p or 1080p there isn't option for it!
but with other resolutions there are two options (Hi/Low)
in these resolutions I have problem !!

View attachment 853363
View attachment 853365
Click to expand...

2160P HiDPI means rendering at 7680x4320, did you check that?
3840x1080 HiDPI.png


What you see in the system preferences is the UI Looks like resolution. The actual rendering resolution need to be checked at system info.
 
  • Like
Reactions: geo88
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back