WindowServer freezes for a few seconds when BetterDisplay is open

[PuzzledUser]

Reading #3154 got me thinking. For some time I've noticed my UI will randomly freeze (like described in https://apple.stackexchange.com/questions/407774/my-macs-ui-is-randomly-freezing-for-5-10-seconds-throughout-the-day-how-can-i). I've been ignoring it for a while.

However, I realised that it only does it when BetterDisplay is running. I never see it when it's not running. When it happens, I might see the UI freeze (mouse pointer still moves) for a few (5-7 ish) seconds. It just did it whilst editing that line of text.

Now for more info and stuff that will offer hope to tie it down, but ultimately just create more uncertainty. I tried various older versions to see when the issue began. Bear in mind I can't reproduce the effect on demand; it might take 5 minutes for it to happen, sometimes it happens several times a minute. Quitting BetterDisplay brings instant relief.

Over the last few days I tested V2.3.9, 2.3.4, 2.3.0, 2.2.0, 2.0.7 and then went back to 1.4.15. All show the issue, I didn't expect that. It is maybe more common in 2.3.9, but I don't have a quantitive test to count/log the occurrences. A ping in local Terminal doesn't show any glitch when the freeze happens. I haven't noticed anything in Console logs. I don't know of a test that logs UI responsiveness to narrow this down.

Any ideas how to track this down? I've run a couple of Samples of WindowServer after a freeze, but that didn't include the string better.

I'm a Mac mini M2 24GB 1TB, Sonoma 14.5 (23F79), plus Studio Display. I typically use one dummy of 960x720. Sometimes I run PiP, but not always and it makes no difference. I used to use a 5k iMac from 2014, it didn't have this issue.

[PuzzledUser]

I just did two more tests:

1. Restarted with not opening previous windows (and with BetterDisplay set to auto launch) and when Finder appeared I found scrolling my List view Applications folder sluggish with some long freezes.
2. Restarted with BetterDisplay set to not autolaunch and found everything silky smooth.

Clearly I must be in the minority here otherwise there'd be uproar. But help would be appreciated.

[waydabber]

Uhh. Something is probably wrong, but had no such feedback about the app so far.

I had various random UI freeze issue with Macs I owned over the years for unknown reasons now and then, could was always a pain to pinpoint an issue like this, so I understand how frustrating this can be. The problem went after away a while for whatever reason. All I could do is start console logging and see if there is anything that might cause this issue and work from that (but you already did that and found nothing).

If it happens only when BetterDisplay is running, it is an obvious indicator that it has something to do with some displays. :) BetterDisplay should not be doing anything constantly particular in a background process that should cause an issue like this but uses some stuff (like queries displays, display configuration dictionaries etc) which are normal things to do - however if there is an issue with the WindowServer configuration it can trigger a who knows what kind of glitch.

You can try starting BetterDisplay with logging from Terminal and see if there is anything the app itself is doing (maybe for any reason it's in an endless reconfiguration cycle or something):

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay -v

I assume you tried resetting the app to see if a baseline app installation has this issue.

You might also want to try to reset the WindowServer configuration files or if you want to go deep, try if the issue arises with a new install (on a secondary APFS volume, it's a quick thing to try) to see if it's a hardware config induced issue or something else. You might also want to try MonitorControl or some other display management apps to see if there is a similar issue.

[waydabber]

Note: I'll move this to discussions, but if there is a bug or some problem that is actionable, I'll open a specific Issue for that.