Waiting for reply from friend. But for me the lagging (also while scrolling) on firefox was made better/fixed after I disabled the firefox accessibility service.
"To try, navigate to the config editor by typing about:config in the address bar, then search for accessibility.force_disabled. It should be set to 0 by default, edit the value and set it to 1, then restart the browser."
It didn't happen when I was using chrome, so I'm unsure if this is the thing that might be causing it.
good to know! ill put this in a computer tag so i can find it