User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0

Steps to reproduce:

mouse scrolling is fine, smooth just like any other browsers.

however scrolling with arrow keys is really stuttery, it is perfectly smooth until you hold the key down and it becomes extremely choppy

i tried to disabled all add ons and it is the same

Actual results:

keyboard scrolling is smooth when you only press arrows one time at a time, but when you hold arrow keys it will be extremely choppy.

Expected results:

it should be smooth as well when holding arrow keys