UI Lags/Stuttering Animation

[Tuan2002]

I just want to share a comment that I have come across on Reddit:

After doing some reproducing at an Apple Store: the bug affects every base (non-Pro/Max/Ultra) Mac. Still not fixed in 26.5, as well as 27 Beta.

I filed a report in Feedback Assistant against the beta, which apparently has a slightly higher chance of being addressed. Every similar bug report (against 27, they're done with 26) helps the cause. I'll be also posting to Apple's developer forums. Would be great if someone posted on MacRumors, etc. as well. If we want to ever see it fixed, we need to make as much collective stink about it as possible before the beta season ends.

Meanwhile, if anyone's interested, I vibe coded a lil background app that constantly screen records a 1x1 px area to keep the animations fluid. I can put it on GitHub with the source code if anyone's interested.

My bug report:

Base M-series (non-Pro/Max/Ultra) Macs render Finder Quick Look and other system animations at ~30 fps unless screen recording is active.

Affects: Quick Look, all animated window and system dialog pop-ups (e.g. Restart, Shut Down)

How to reproduce:

1. Open Finder on any base M-series Mac
2. Press Space on any non-video file
3. Observe ~30 fps animation
4. Start any screen recording
5. Repeat steps 1 and 2
6. Observe fluid animation

Present in macOS 26 and macOS 27 Public Beta.

Reproduced on multiple base M4, M5 and A18 Pro Macs in Apple Stores.

Not reproducible on Pro/Max/Ultra variants.

Reproducible on a clean installation.

Screen recording immediately restores 60 fps in all animations.

Affects system UI, not just Finder.

Original comment link: Reddit comment

 

[SketchyClown]

OK, so this is why random Reddit comments are so annoying.

So in my experiment with the screen recording tool open & recording, hitting the space bar to quick look items in the Finder has no overall effect that I can see to the "speed" of the animation of quick look versus when it's not open and recording.

However, when you watch the screen recording that was made, I would say yes, the animations appear to open quicker.

So what I can deduce from this is that the screen capture tool is recoding in HEVC 60fps. Anything you watch that is recorded in 60fps looks different (better? more fluid?) than 30fps.

So assuming that the screen recording tool somehow fixes and exposes a bug in the UI animations is false from what I can see.

macOS 27 is currently in beta. Refinements and tweaks are still being made to all aspects of it. Comparing it to the bloated mess of 26 is not something you can really do here.

 

[benholt]

For a data point on the higher tiers: I ran the repro on my M3 Max MBP and M2 Ultra Studio, and Quick Look animation is fluid on both, with or without a capture running. Matches what the OP is describing (Pro/Max/Ultra unaffected).

On the "recording fixes it" part — I don't think it's just a 60fps perception artifact from watching the recording back. When a screen capture is active, macOS pins the display to its higher refresh path instead of letting the compositor dynamic-clock down. It actually changes what's being rendered in real time, not just what's saved. Whether base Macs are hitting a genuine bug or an overly aggressive power-saving path is the more interesting question.

 

[galad]

That's because the new glassy background requires more GPU power, and the GPU doesn't ramp up its frequency fast enough.

Screen recoding causes additional GPU usage, so the GPU is already at a clock speed that can run the animation and the glass background at 60 fps.

 

[opn]

I'm the Reddit poster, thanks for sharing! Check out the (literal) screen recordings I made in slo-mo with my phone (27 public beta 2).

No screen recording running:

Screen recording running:

 

[hieubui]

OK, so this is why random Reddit comments are so annoying.

So in my experiment with the screen recording tool open & recording, hitting the space bar to quick look items in the Finder has no overall effect that I can see to the "speed" of the animation of quick look versus when it's not open and recording.

However, when you watch the screen recording that was made, I would say yes, the animations appear to open quicker.

So what I can deduce from this is that the screen capture tool is recoding in HEVC 60fps. Anything you watch that is recorded in 60fps looks different (better? more fluid?) than 30fps.

So assuming that the screen recording tool somehow fixes and exposes a bug in the UI animations is false from what I can see.

macOS 27 is currently in beta. Refinements and tweaks are still being made to all aspects of it. Comparing it to the bloated mess of 26 is not something you can really do here.

It’s about slow or quick. It’s how fluid the animations are rendered. And doesn’t have to watch the recording to know. See the videos recorded by phone above this post.

This “bug” is well known beyond macOS. iOS has been having this for years. Start screen recording the UI instantly become smooth, most visible in the App Library.

Either this is a bug or it’s their aggressive power saving strategy, sacrificing user experience.

 

[opn]

Also, other UI animations are always perfectly fluid (27 beta), like minimize to Dock or Mission Control, which has to be way heavier on the GPU than a dialog pop-up.

 

[F1Mac]

Speaking of minimizing to Dock... Sometimes the genie effect just doesn't show at all, clicking on the orange light just makes the window disappear (no matter which application you're in), or it just works on a portion of the screen but not entirely to the dock like it's supposed to. I suppose that's a small bug that will get fixed but it was present in the first beta and it's still here in the latest beta.

 

[SketchyClown]

I'm the Reddit poster, thanks for sharing! Check out the (literal) screen recordings I made in slo-mo with my phone (27 public beta 2).

No screen recording running:

View attachment 2648638

Screen recording running:

View attachment 2648639

I have no idea what hardware you are running this on. Also those are filmed in slo-mo? I'd hope so or you have a definite issue. 🙂

I'm on a M4/512/24 MBA and this particular animation for reboot or shut down appears fluidly and extremely quick here when requested, as do all of my UI animations. I see no issues.

I am not sure what hairs you are trying to split with this, but clearly it makes a difference to a handful of you so I'll bow out of the "experiment". Good luck to all!