I made a real quick video in order to compare the performance of my MacBook Pro (13-inch, 2017, 3,5 GHz Dual-Core Intel Core i7) before and after installing the new MacOS Big Sur over Catalina. The video shows the boot sequence as well as a Geekbench 5 run. I was actually surprised to see the result. Sorry it's so crappy, but you get the point.
