More scripts = more lag?

I just want to know, if I do thousands of scripts, even if it’s short scripts, it’ll affect the performance?

Yes, each time the engine has to call into an Update() or FixedUpdate() method, even if it’s empty, it will incur a performance hit. So yes, thousands of short scripts will still affect performance.

It all depends on what those scripts are doing. If they are calling a method which is constantly update (for example Update() and FixedUpdate()) you are going to see a performance hit. If they are just storing variables (I’d recommend not doing this), then you won’t see a performance hit. It may use slightly more memory though.