I have an older Surface tablet (that I recovered from a recycle bin, TBH) and I've been using Chrome on it, but I was annoyed by some of the latency and tried Firefox the other day. It had all the problems of Chrome, plus jittery scrolling and some extra random lags thrown in, so I noped right out of it. I've got nothing against Firefox as a concept, but it's apparently too hardware intensive for that scenario.
Are you sure it isn't the hardware? Perhaps there's a reason it was in the recycling bin. Not my experience whatsoever, even with "old Surface tablets".