Vsync is broken (Linux)

[linavixx]

Captchas

• I have read the instructions.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

Since the update to FF 137 (IIRC) scrolling became choppy for me, with the browser feeling way too slow overall even though I didn't change any settings that should affect this and it uses HW acceleration. I found the scrolling optimizations issue, but it doesn't match what's happening for me, because my CPU/GPU usage is normal and none of the tweaks proposed in that thread (disabling gradient, compositor etc) did anything for me. It doesn't matter which page am I looking at, not even about:config is smooth.

When I ran ufotest, I noticed that it always fails to Vsync and can't run the test smoothly (instead of matching my monitor's 144Hz, it jumps from 139 to 143). Makes me think that Vsync is what's no longer working and thus making it lose the smoothness, or something else is causing consistent stutters preventing it from syncing. This isn't present on latest Firefox, nor did it happen there recently. Only addons I have are Ublock Origin and FastForward, both on Zen and Firefox.

I'm using latest Arch Linux with Sway WM (Wayland), RX 6800 AMD GPU and Mesa drivers.

Version

1.11b

What platform are you seeing the problem on?

Linux (Tarball)

What component is this issue related to?

Performance

Relevant log output if applicable

[chermnyx]

This might be related to #6302

Also it might happen if you have turned on webrender compositor (it's allowed to be enabled on linux via about:config starting from Firefox 137)

[linavixx]

Also it might happen if you have turned on webrender compositor (it's allowed to be enabled on linux via about:config starting from Firefox 137)

I'm aware of it, but none of the suggestions in that thread improved my situation, including disabling the compositor, and I always ran it without rounded corners. Moreover, I had webrender and compositor enabled for a while in vanilla FF and it doesn't have any performance hiccups. The issue also appeared only a couple days ago (137 release I presume), while the thread is much older.

[chermnyx]

I can confirm frame rate jitter on testufo which does not happen on Firefox (i'm using kde on wayland), but the scrolling is smooth for me

[linavixx]

Somehow, both problems are gone after fully reinstalling Zen. Closing.