I don't know what exactly dragonchild was referring to, except that if you create methods or classes on the fly, that's going to consume memory. No more so than if you'd put the same definitions in a .pm file and use'd it, though. I don't think AUTOLOAD or eval("string") themselves leak memory. And I don't know what "compile time optimizations" he was referring to; eval is as much compile time as what you get when you load your main program or use/require'd modules.