Hi there, Exactly same problem here: Safary is completely unusable after big sur upgrade from cata on a MBP2018. No problems with firefox dev ed, chrome or brave. I have just reinstalled again as sugested by an apple tech, but no luck... I also think that there are other problems related to this one: for instance, programs like VSCode does not start inmediately. It seems that they try to stablish a tcp connection but they cannot, so there is a 10 secs time frame, even more, before the application continues loading :S. Really frustrating! I hope it get solved somehow, but I think even apple care techs do not know how to isolate and handle the problem.