I have been looking at improving my asp.net page performance, is it worth changing autoeventwireup from true to false and adding the event handlers or is the performance pen
The performance is 0, because once wired up (once your application is compiled in memory), it never has to do it again. What I mean by that is, the ASP.NET framework isn't constantly itterating through every method by name to see if it should be wired up.
But, I strongly suggest you turn it off, because it usually causes issues of double page loads or whatever (if you wire up an event yourself, but due to naming it a certain way, ASP.NET wires it up too).
That's a feature that I wish was defaulted to off.