Firefox Support Forum

I added a screenshot of youtube having flickering while video is being played, it is a bit hard to see but there is a slightly brighter stripe on the grey background and picture cant depict flickering; it starts immediately after video is started and stops after 3-4 sec after video is paused, like there is some background activity behind youtube foreground. I understand my comp is weak (Intel Iris Graphics 550 1536 MB 8 GB, 2133 MHz LPDDR3), but not that much, please help

If I lock my machine for more than a few minutes and then log on again, it's always the same. I unlock my system and feel some kind of slowness in Firefox. When I switch from the currently open tab in Firefox, the new tab is highlighted in the tab bar, but the content part of the window is frozen. If I quickly open htop, I can see that the main Firefox process is suddenly using about 130% of my CPU. The only solution I have found is to quickly open htop after unlocking the system, send a SIGKILL to the main Firefox process and reopen it. This way the freezing, slowing problem is nowhere to be seen.

I am running Debian 12 with Firefox 115.4.0esr (64-bit). I have more than enough RAM and CPU.