Not sure if this is the right place to post but in connection with Big Sur, I am very disappointed with its speed. I bought a new Mac last year because after talking to Apple about the slow speed of my old Mac, I was told it was too old and a new one would be much faster. It was till I updated it to Big Sur 11.1. Now it's as slow as my old one, slow starting up and slow to open the apps. I have used very little memory space.
Just curious, what type is your Mac? Newer OSX version (including Big Sur) are optimized for SSD.