Lower performance for 3D games in HiDPI mode compared to LoDPI mode (note: this is normal)

[stantios]

Description: The mouse seems to be lagging a lot when moving around with my mouse, using WASD on my keyboard, and spam clicking with left click. If I quit BetterDisplay, this issue does not happen. I mentioned WASD because this issue was happening when I was playing games like Hytale or Minecraft.

I wanted to also mention that this issue still happens on the default settings for BetterDisplay.

Video showcasing the issue:

video.mp4

Reproduction Steps:

1. Load default settings for BetterDisplay.
2. Load up a game like Minecraft or Hytale.
3. Try and see if while moving around, you experience any lag.

Mac Model:
MacBook Air (13-inch, M3, 2024)

macOS Version:
26.2

Other Information:
Display Mode: 2048x1152 (16:9, 48-1080Hz, 10bit, HiDPI)
Refresh Rate: 48-180Hz (Variable)
Colour Mode: 10-bit (SDR, RGB, Full Range)
Colour Profile: Q27G3XMN
High Resolution (HiDPI): On

I think this might be an issue with the resolutions that BetterDisplay providers. If I switch to 2048x1152 provided by macOS when BetterDisplay is disabled/is not running, it seems to work fine and the lag is gone.

[waydabber]

Are you switching to 2048x1152 HiDPI or LoDPI in macOS System Settings when you are not using BetterDisplay? 2048px HiDPI is a 4K+ resolution which might be a bit much for a MacBook Air for a 3D game.

[pkarthi92-star]

@waydabber Even I face the same issue. I use better display just for mirroring (using the stream virtual screen option). When I do this, my mouse pointer lags a lot. Sometimes upto 5 seconds too. I use 3 displays (1 x 1080p, 1x 4K , and 1 x 1080p for teleprompter)

As soon as I disable streaming, everything seems fine. Been struggling with this for an year.

I use M2 Ultra Mac Studio. So I dont think the system is an issue. I am use the licensed version of Better Display and have stopped using it just due to this issue. Otherwise, its a brilliant app.

[waydabber]

I am not convinced that these are the same issues. @stantios seems to be using a native display, and the performance seems to be related to 3D games (where a HiDPI framebuffer requires 4x as many pixels to be pushed). The issue @pkarthi92-star describes seems to be a screen streaming issue - this really depends on how things are set up: Is the 1080p stream 1080p LoDPI or HiDPI (which is 4K) and how is the display connected? Usually slow streaming performance affects software displays (like Sidecar or DisplayLink) where the stream taxes the USB connection (that pushes through the compressed video data) as with streaming the entire screen is recognized as changing ("dirty") instead of only specific smaller regions - this has a serious performance penalty, especially at USB2 speeds. This issue is unrelated to 3D graphics and does not depend at on the power of the computer (the M2 Ultra is powerful indeed).

[pkarthi92-star]

Really appreciate your response. The monitors are connected directly using HDMI port and USB C ports. I am not using HiDPI as far as I know.

The monitor I am streaming the signal is 1080p but the stream still 720p. Would be great if you can help resolve this. Attaching screenshot for your reference.

[pkarthi92-star]

I am using the streaming option, not sure if thats the most optimal way. My only requirement is to mirror flip a display for teleprompter.

[stantios]

Are you switching to 2048x1152 HiDPI or LoDPI in macOS System Settings when you are not using BetterDisplay? 2048px HiDPI is a 4K+ resolution which might be a bit much for a MacBook Air for a 3D game.

I am switching to the standard 2048x1152, there doesn't seem to be a HiDPI option available for that resolution. Screenshot is below of which resolution I used:

The thing is, if I switch to the standard/LoDPI option from macOS, I get really weird rendering which you can see below:

Compared to BetterDisplay 2048x1152 HiDPI where it is really clear:

[waydabber]

It seems like the second image is the low resolution variant (although you say it's HIPDI), the first one is the high resolution. Logically the first one should be slower (the HiDPI version) as that requires the GPU to process 4x as many pixels which will slow down a 3D app. I assume the screenshots are just mixed up, but the LoDPI vs HiDPI difference explains the slowdown sufficiently. I recommend playing 3D games at the native resolution at most to maximize quality, or downsample (set a lower-than-native LoDPI resolution) if there are performance issues.

[stantios]

Is there a way to detect when a certain app opens and set the resolution to specified option? The resolution could reset to the default value once the app has been closed. This allows those resolutions to be used only when those apps are opened.

Also, the text appears really blurry on apps when using the LoDPI version of 2048x1152.

LoDPI Version:

HiDPI Version:

[waydabber]

Yes, LoDPI is blurry. You should use HiDPI unless you need LoDPI for a 3D game. Some games allow changing the rendering resolution independent of the UI resolution - you don't need to switch modes then. You can create a macOS Shortcut to change the resolution + launch the game if needed, or you can assign a hotkey in the app for a desired resolution.

[stantios]

Some games allow changing the rendering resolution independent of the UI resolution - you don't need to switch modes then.

What resolution would I change it to?

You can create a macOS Shortcut to change the resolution + launch the game if needed, or you can assign a hotkey in the app for a desired resolution.

This is a very nice thing to have, I just set this up now.