@CatWEax
Interesting how it only affected Firefox on Linux, there shouldn't be that significant of a difference between the Linux and Windows version. I might have to look into it a bit more. I just loaded some JavaScript to delete the element as i found that position:fixed didn't quite fully...
Specs:
Firefox 68.01 and 69beta on Manjaro Linux
Extensions Disabled
Tested with WebRender Enabled/Disabled
Tested with JavaScript Enabled/Disabled
I noticed upon opening the reader page for manga, my CPU usage would spike up to 200% and maintain a 100%+ utilization while the reader was open...