There is no practicable way to "undo" a macOS upgrade. Your best course of action is to determine the reason those apps are crashing. It may be something you can fix, or it may require the developers of those apps to update them for Sonoma. Considering they have had the ability to test prerelease macOS versions for months by now, consider the possibility they simply aren't interested.
In any event upgrading macOS should not have made your Mac become slow. The first step in diagnosing poor performance should be to determine if the same problems occur in "Safe Mode": How to use safe mode on your Mac - Apple Support.