I have just installed Photoshop Elements 2021 on my newly purchased Mac Mini running Big Sur. The Editor works OK, but the Organizer is very slow. It is impossible to scroll through the gallery of thumbnails. Opening and closing thumbnails by double clicking takes 3 to 6 seconds in each case. I have been using Photoshop Elements very happily with older versions for very many years now, and I am puzzled and disappointed to find that this up-to-date software on an up-to-date computer is simply not fit for puurpose.
Mac Mini (M1, 2020); macOS Big Sur 11.5.2; 8GB RAM