Why am I timing out when using the Menu Editor?

Well, with custom menu’s there can not be any conflicts because, If I’m not mistaking, menu that has a name of a deleted one, will be assigned a new ID and/or a slug so it would be different from the old one. The only thing I can think of is that there is a problem with your server or MySQL which either is very slow or just not working. Also, did you try a different browser? A long shot, but nevertheless worth a try.