Hello,  

        before a few months we updated on two stations Solid Works 2020 SP4 to last licence allowed version Solid Works 2021 SP3,

  and it was dissapoint-full thing ever...  Please watch videos at links below ...how it behaves and offer please remedy.  

https://icw.li/2LYGhRFHR

We use two different hardware on Windows 10 and it is same   

HW configuration Old station is CPU I7-7700