Changing that option doesn't change anything in my subjective feeling. It's not only scrolling that is laggy, I think. Also I didn't change any settings between a week ago and now, still suddenly it got laggy. It works fine on my iMac (albeit an older Intel iMac) with the exact configuration. (I use Firefox as my work browser and since I usually work at the iMac, it's been a week or two since I've last used Firefox on my M1 MBA.)