This particular issue was fixed.
- Hangs and endless loading screens have multiple causes. Outdated Mods is the most common one. Please see this post for further details: Game hangs on loading.
- TwistedMexi found that if you have a lot of mods, the modding list shown at the beginning can cause very long loading times. Make sure to turn that off.
My game freezes for a few minutes when loading the game. After it loads, I have no issues in game.
Patch 1.21 seems to cause some issues with reading the screenshot folder. If you have tons of files in that folder, the game will show above symptom.
Clean out your screen shot folder or move everything to a save place.
500 files already seem to be too much. It may depend on your computer though.