Level1 Dark Theme (Default) Skippy with Linux+Firefox

Not sure if its me but there is a fair bit of frame skipping when scrolling with the Level1 Dark Theme which is default dark theme on this forum.

The other themes do not exhibit this issue, so, may I suggest L1Tech guys take a look at their theme file, or rebuild it with the Material Design Theme as the base, because that works fine. (also Discourse Black is fine but font and paragraph settings are too large)