What exactly affects the gameplay that slows down the game?

Hi, I would like to know what exactly affects the gameplay that slows down the game? I recently made such a decision that there may be a large number of scripts that slow down the game, and I have reduced them and now I have no more than 100 of them.

alot

physics parts, players, scripts that require things to transfer over from client to server or vise versa, etc.