Created attachment 1631991 [details]
Firefox support log
*This bug is created upon a request on Fedora Mag.
Firefox seems much slower on Wayland than X whether ran natively or through Xwayland. (this stands for the Nightly version too, in addition to the package provided by fedora)
The lags/stutters are pretty noticeable when scrolling or when there are CSS animations. This has gotten a lot more visible (somewhat unusable) with the new kinetic scrolling. Also on websites such as Pinterest you can noticeably see that images are rendered as white when scrolling at speed.
I have Webrender enabled here, but turning it off doesn't make the situation any better.
(also probably not related but Wayland is generally pretty slow for me, and keeps getting slower each version, in contrast with people people noticing huge improvements, so not sure if this is something about my particular hardware. another note is that Firefox on Wayland was pretty smooth at the early stages for me, back when enabling acceleration would cause it to crash, so not sure if a regression)
Hardware: i7-4720HQ, running Firfox on my GTX 960m via Primusrun is also pretty slow)
The support page log is attached.
Thanks for reporting this, we'll look at it.
I think https://bugzilla.mozilla.org/show_bug.cgi?id=1583732 can make a difference for you as it brings better back buffer management. Please try latest nightly but *without* webrender/gl compositor. Also do you see extensive CPU usage or you see the slowness/lags while CPU usage is low? In that case it may be https://bugzilla.mozilla.org/show_bug.cgi?id=1542808
I tested the latest Nightly with force-disabling Webrender and having "layers.acceleration" off and it was really slow. But I indeed noticed more CPU usage compared to X when scrolling even on very simple pages like "about:support".
I am using Firefox on Wayland with two displays. One display is scaled to 150%, the other 100%. When I have Firefox on the 150% display it is extremely slow when 'scrolling' trough the media of a Twitter account. When Firefox is on the 100% screen it is way faster.
I use Firefox full screen.
Can you try to use 200% scale instead of 150%? I guess the experimental partial scrolling feature may be the factor here.
Also can you try to enable WebRender? Set gfx.webrender.all to true & gfx.webrender.enabled to true at about:config and restart browser.
I can reproduce this issue. I have a 4K monitor scaled at 120%, and a 1080p monitor scaled at 100%.
Changing to the monitor to 200% scale fixes the scrolling lag.
Enabling webrender (at 120% scale) also fixes the lag, but windows on my 1080p screen don't render properly (the window content takes up about 1/4 of the screen, but the window border behaves as expected). That seems like it would be a separate issue, though.
I think there's a problem with GPU acceleration in Firefox in Fedora... I have an AMD GPU (RX 580) with free drivers... Firefox with Wayland doesn't run with GPU acceleration enabled. When i enable, Firefox automatically run with XWayland, no way to have HW acceleration with Wayland.
(In reply to makal from comment #8)
> I think there's a problem with GPU acceleration in Firefox in Fedora... I
> have an AMD GPU (RX 580) with free drivers... Firefox with Wayland doesn't
> run with GPU acceleration enabled. When i enable, Firefox automatically run
> with XWayland, no way to have HW acceleration with Wayland.
That's very strange. I have RX 570 and that works very well with HW acceleration enabled with free drivers. But I don't use experimental partial scalling, just 200% scale.
(In reply to Martin Stransky from comment #9)
> (In reply to makal from comment #8)
> > I think there's a problem with GPU acceleration in Firefox in Fedora... I
> > have an AMD GPU (RX 580) with free drivers... Firefox with Wayland doesn't
> > run with GPU acceleration enabled. When i enable, Firefox automatically run
> > with XWayland, no way to have HW acceleration with Wayland.
> That's very strange. I have RX 570 and that works very well with HW
> acceleration enabled with free drivers. But I don't use experimental partial
> scalling, just 200% scale.
I can enable HW acceleration and it works well, but in x11 mode, not in Wayland.
Enabling like this :
- gfx.webrender.all to true
- layers.acceleration.force-enabled to true
Even i run with "MOZ_ENABLE_WAYLAND=1 firefox", Firefox stays in x11 mode (shown in about:support)
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