Get you into the game and playing!
This assumes the obvious of making sure everything is up to date on your PC.
1. Disable Steam Cloud Synchronization. (google if you don’t know how)
2. Disable or Dis-Allow ANY Cloud software you are running.
3. Disable ALL Firewalls and AntiVirus. (to see if its the problem)
4. If you are using steam offline mode, try going online. If you are online, try going offline.
5. Disable Spotify, Discord, RivaTuner, MSI Afterburner, GeForce Experience, etc.
Time To Get Dirty
6. Go to C:\Users\*YourUserName*\Saved Games\Frontier Developments\Planet Zoo\
6.1 Delete all files.
(you will obviously lose your saves, but they could be the cause. back them up if you want, but I suggest trying everything else here with them deleted first)
7. Try launching the game in Window mode.
Steam Library | Right Click Planet Zoo | Click Properties | Click Set Launch Options | Enter
8. Set your monitor refresh rate to 30hz. Set the game to 30hz in the NVIDIA Control Panel.
9. Try starting Windows in Safe Mode. (google it)