Bug 1768135

Summary: Firefox is really slow on Wayland
Product: [Fedora] Fedora Reporter: zareami10
Component: firefoxAssignee: Gecko Maintainer <gecko-bugs-nobody>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 31CC: 0xalen, anto.trande, gecko-bugs-nobody, jhorak, john.j5live, kengert, pjasicek, rhughes, rstrode, sandmann, stransky
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Hardware: x86_64   
OS: Linux   
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Bug Blocks: 1054334    
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Firefox support log none

Description zareami10 2019-11-02 20:10:44 UTC
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.

Comment 1 Martin Stransky 2019-11-04 17:10:21 UTC
Thanks for reporting this, we'll look at it.

Comment 2 Martin Stransky 2019-11-05 10:16:59 UTC
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

Comment 3 zareami10 2019-11-05 16:57:24 UTC
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".