User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0 Steps to reproduce: Enable layers.accelerations.force-enabled. Launch: DRI_PRIME=1 firefox Actual results: At first, the scrolling was normal, then it became that if I stop scrolling for a while in some websites, there'd be lag after scrolling, then I'd see the result of scrolling. Info: - OS: Fedora 29 KDE spin (64 bit). - Laptop: HP Pavilion g6. - GPU: Intel/AMD Radeon HD 7670M. I used the AMD GPU. - RAM: 8 GB. Notes: - The problem always existed regardless of the distribution. - It might also exist in Chrome. I'm not sure; I didn't use it for a very long time. - Hardware acceleration's very important. Please, enable it by default in Linux. Expected results: Scrolling is always smooth.

(In reply to ali.sherif10 from comment #0) > - Hardware acceleration's very important. Please, enable it by default in Linux. It's being worked on. You could try out WebRender: https://nightly.mozilla.org, open about:config, set gfx.webrender.all to true and restart Nightly. But there are still a lot of optimizations to come. https://mozillagfx.wordpress.com/ https://hacks.mozilla.org/2017/10/the-whole-web-at-maximum-fps-how-webrender-gets-rid-of-jank/

I did it. You can see my feedback at bug #1278719 comment #35.

After browsing for more than an hour, the lag returned. Maybe it makes Firefox slower quickly after cache accumulation? Is it related to my GPU being old?

I used Gecko Profiler on Firefox Nightly from Flatpak. I noticed 2 scrolling lags in https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Profiling_with_the_Built-in_Profiler. Note: I added DRI_PRIME=1 to the beginning of the launch command to use AMD's GPU. Result: https://perfht.ml/2BtYJdb.

I think this is a duplicate, because lag happens after waiting for seconds.