1748800 - Firefox is capped at 60 fps on Linux even with 180 Hz monitor

Status: UNCONFIRMED

(Core :: Graphics, defect)

Description

[Shmerl]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:96.0) Gecko/20100101 Firefox/96.0

Steps to reproduce:

I set layout.frame_rate = 180 in about:config to match my 180 Hz display. I can see that "Target framerate" is shown as 180 in about:support.

Then in KDE Wayland session (Plasma 5.23.5) I ran performance recording from developer tools. It shows max framerate as 60 fps on the left, which supposedly indicates that it's still artificially capped at 60. Is there some way to uncap it?

Also, "average framerate" shown on the right there is fluctuating and can be higher (even approaching 180 sometimes), which is confusing since max is shown as 60 on the left still.

Comment 1

[Darkspirit]

Thanks for the report! Please open about:support, click on "Copy text to clipboard" and paste it here.

Comment 2

[Shmerl]

Attachment: about:support

Comment 3

[Shmerl]

Just to clarify. I'm not sure if it's actually the bug with capping, or it's a bug with reporting in Firefox developer tools when recording performance. In either case, something wasn't correct.

Comment 4

[Shmerl]

Someone suggested to set these to check the actual framerate:

fx.webrender.debug.profiler-ui=FPS
gfx.webrender.debug.profiler=true

I tried that and I can see the meter and the value goes above 60! So it must be not the problem with capping, but with built-in Firefox performance meter tool that has some misleading info there.

Comment 5

[Dzmitry Malyshau [:kvark]]

Thank you for filing!