Photoshop 2021 slow with certain tools

Hi all,
I've updated my Photoshop to 2021 version but I'm having some issues:
When I zoom in it become very very slow and laggy, using the pen tool is very hard due to this lag.
I've disabled the graphic card accelerator and zoom is now ok but I get a lot of strange grey squares appearing when I working and doing stuffs like panning, using the pen, using curves and so on.

Any advise?
I'm running Macbook pro 2018 

  Model: MacBookPro15,1

Graphic Card: Radeon Pro 560X 4GB

Processor name: 6-Core Intel Core i7

  Processor speed: 2,6 GHz

  Processors: 1

  Cores number: 6

  Cache L2 (per Core): 256 KB

  Cache L3: 9 MB

  Hyper-Threading: On

  Memory: 16 GB

  Version Boot ROM: 1037.147.4.0.0 (iBridge: 17.16.16610.0.0,0)