Thanks for the message. Sounds like you are having multiple issues with v.23 or 23.1. We could use a little more info to help. Which OS are you on? What kind of computer, and what are its components? On Windows with an NVIDIA GPU? If so, is that the driver version? What kind of footage is it in terms of codec, frame size, frame rate, and any other workflow things that might be hard to see from here. Is it a multicamera project? A long film?
With more info, the community can make suggestions.