Doubtful.. I would imagine they run just the same. If all you're doing is changing the appearance of the code, variable names, etc., the parser isn't going to have any problem with it, and the resulting bytecode will be indistinguishable. If, however, you're encoding your strings, doing some unusual looping or whatever, you're going to incur some slight penalties if a lot of work normally done at compile time is going to be done (esp. repetitively) at run-time. It all depends on how you go about doing it.