Are you running ff at your monitor recomended resolution? From that very long list I can see ff is running in 1920x1080 mode. If its not compression artefacts we are seeing in your picture I would say you have a resizing issue.
Have you tried running in windowed mode? Does the problem persist there, if not you need to double check resolutions if it does check all the graphics options you get at settings while at the login menu.