The overhead is tiny, less than milliseconds for sane modules. It's a useless optimization, especially when it can be done at install time only, say, as opposed to for every module import, but even that is somewhat silly.
Without seeing any numbers, it doesn't mean much to me. I'm assuming someone much smarter than me has identified the benefit of bytecode caching and unless it really gets in my way, I see no need to do away with it.
