Problem with UI in projects using Mozilla

Good day,
Just wanted to ask the community if anyone experiences problems using Mozilla browser?
I’ve reinstalled by browser and set codecademy to have security exception.
However in projects I get a lot of strange behavior, the UI flash when scrolling through exercises and type in the code editor is very slow. It is nice feeling like a pro hacker as inputs smoothly appear like syrup flowing off a spoon.

Depends which version I guess?
I run the latest Firefox Quantum and no problems around Codecademy.
Although, it can be a bit sluggish. Chrome definitely runs faster.

Perhaps it has to do with some addons that you have installed?