My 2020 13" mbp "feels" snappier. But VMWare is broken (windows XP virtual machines are abysmally slow), streaming HomeKit secure video now makes the fans scream (on Catalina the fans were silent), mail no longer automatically imports calendar invites from gmail, and the super-rounded window corners waste a lot of screen space. I should have waited a couple months.
The new version of Fusion that was just released works great on Catalina (including XP VMs, even after upgrading the hardware to the latest version). You may want to try 12.1 to see if it works better on Big Sur...I can't say as I am still using Catalina as my host.