Maybe, but I've been noticing the same in the late week or so. Github was actually unbearably lagging the other day and some pages perform really terribly on occasion. It's probably some of the new haphazardly implemented garbage from manifest v3, after all it's all about Google shooting the browser in the foot to save their adsense business.

I haven't really checked if it's better on FF because it can't screenshare specific tabs so it's dead to me.