Yo, Linux sysadmin here and been using Firefox forever.  Surprisingly I have this ancient 12 year old System76 laptop that I use for nearly everything (got a newer Lenovo that I been meaning to switch to but no time). Using Debian 12/13 with Gnome 43.6/X11.  Can't quite figure out this issue though.  Besides being a sysadmin, can have other side jobs/projects going on as well, so can have 5-10 windows open in different workspaces, sometimes with hundreds of tabs all together (big fan of the Auto Tab Discard add-on and about:memory Minimize Memory Usage to keep performance up and resource usage low). Been noticing this issue for the last few versions where suddenly, after random amount of Firefox uptime (can be after days of perfect performance) my keyboard input aka typing gets extremely laggy, like 30 seconds behind for all keystrokes, ''except'': Ctrl-F instantly brings up the Find in Page bar, and Ctrl-C instantly copies to clipboard.  Ctrl-V, however, 30 seconds lag, Ctrl-A also....  Mouse is fine though and can right-click and paste instantly or use other menu options.  Happens anywhere in Firefox too: in address bar, in the find text box, in the preferences, in my saved passwords, haven't found a place with no lag. Have searched around for some hours now and only found suggestions to disable accessibility service, but '''accessibility service has already been disabled for a while''' now.  Everything else in my Gnome desktop session is running fine.  Restarting Firefox temporarily solves the issue but is highly annoying and interruptive with as much as I have going on sometimes.  Due to timing randomness, starting Firefox without certain add-ons is impossible as I can't spend days at a time without any of them.  Just have to open a text editor and type what I need to in there, then paste with mouse, until I can find a good stopping place to restart Firefox. Have included most of the info from about:support in the Troubleshooting Information.  Spent quite a bit of time looking at all my modified preferences, nothing popped out but if there's something you think I could include to help, let me know. Thanks