I’ve been testing Big Sur on my 2016 MacBook 12″ (8GB Ram, 1.1 M3) for a month or so now and even though I know it’s a beta I don’t think performance is going to get much better on this model. At this point I can’t recommend upgrading to Big Sur if you are running it on a 2016 MacBook. It’s laggy to the point it’s almost unusable in places, I’ve gone back to Catalina and I’ll be sticking to it on this model of MacBook.
I’m yet to try our iMac that also has 8GB Ram and I’m fearing that I won’t be upgrading that one either. Ram seems to be big on this one and I’d recommend 16GB at least if your machine had 8GB or less.