Unlag Neo: A "fix" for the cursor lag on Macbook Neo

Macbook Neo (I'm on macOS Tahoe 26.5.1) cursor is lagging when the cursor is near the screen's edges or when it enters a Terminal window. [1][2][3][4][5]

[Click here for more info and background]

Why is it lagging?

I don't know. But at the moment when it lags the system switches from hardware cursor to software cursor (CGCursorIsDrawnInFramebuffer() goes from 0 to 1) so maybe that transition is stalled somehow on Macbook Neo. Maybe on the screen's edges half of the mouse is rendered and in the Terminal there is some other graphics stuff happening, so that's why macOS wants to use SW cursor there, but idk. For some reason, HW cursor is only used after ~17 seconds after the screen was locked. Before that, there is no lag.

Proper fix:

Either fix the lag directly (hope Apple does it) or maybe forcing to always use SW cursor would help as a intermediate step. To force SW cursor directly we could reverse engineer WindowServer but that probably implies turning SIP off and stuff. Or maybe not. And maybe HW/SW cursor is just a correlation. We could also look what happens ~17 seconds after Mac is unlocked.

Other ok "fix" for now:

You can also turn on macOS Color Filter (e.g. Blue/Yellow filter) to low setting, but this changes the colors a bit and doesn't seem to help if Night Shift is on at the same time. Also the mouse cursor size can be changed. But to keep the colors and cursor ok, we can also do a Screen Recording. However with screen recording there is an indicdator () on the top right of the screen. Maybe it can be disabled with SIP off but I haven't looked.

Essentially anything that forces the compositor(?) to do SW cursor (or whatever else) will do. No lag anymore.

Other idea:

Find out what's special about the Terminal window and create an app that does the same thing and overlays its window over everything.

Anyway, I chose Screen Recording.

My favorite "fix" right now: Screen Recording

For me, the Screen Recording solution is the least annoying one. The indicator () is small enough and we can turn off screen recording when a fullscreen video is playing (where the indicator would be annoying otherwise imho). Obviously, such a fix would invalidate the purpose of that indicator, but I think there are two kinds of indicators. There is a larger one also, which (I think) app store apps have, so I think we are fine-ish.

The cursor stops lagging.

It doesn't need much CPU/GPU:

Record 1 pixel every 10 seconds (to /dev/null basically, no SSD write)

Ok how to do it:

There is a script (create_unlag_neo_app.sh) below in this Gist. The script creates an .app which can be launched (no need for Dev Account or Xcode etc.).

The script can be used like this (Terminal):

chmod +x create_unlag_neo_app.sh
./create_unlag_neo_app.sh
# -> creates "Unlag Neo.app"

App that the script created:

Put Unlag Neo.app somewhere. In /Applications or something. Run it and give it the permission it wants.

In the menu bar () you can turn it off and also try the "Pause in Fullscreen" feature if you want, which does an OK job I think to hide the indicator. I tried with VLC and YouTube and a few apps.

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[[Click here for Debug info]]

Debug

If you want to hack create_unlag_neo_app.sh and rebuild the app multiple times, macOS permission settings UI can reset and behave a bit weirdly. You can try to change "Unlag Neo" to something else in the script, or drag the app icon into permissions settings manually, or try to delete "~/Library/Preferences/Unlag Neo.plist" or killall cfprefsd or just use Xcode.