Author's using Windows.. Latest FF on Windows seems to have issues with rendering. Loading up posts on old.reddit.com leads to the DOM glitching after a few seconds and elements disappearing. Happens frequently on pages with lots of comments. Something glitchy going on.
Your graphics driver is likely faulty, as I have not noticed any such issue with AMD Radeon Vega 64.
I would switch to Firefox if they managed to support the basically unlimited amount of tabs I can open on Chrome without any slowdown or degradation. There's probably a better way to manage it, but when you're going down the rabbit hole of stackexchange and Google to try and figure something out, it's an extremely invaluable tool for me personally.
I always have 7 Firefox windows open across 4 virtual desktops with over 100 tabs across them. Never crashes on Linux and never eats all my 16 GB of RAM. Right now it's using about 4 GB of RAM. When I run Chromium in 1 window with 4 tabs, within hours it's using all available RAM and the tabs start crashing, one at a time, as they fail to allocate more RAM.