As Sean said, don't reset the random number generator in a loop. There's no good reason to do it. You are NOT making your random number "more random", and in fact, you are likely making them less random in very complicated ways. DON'T DO THIS. I can't say that strongly enough.
'shuffle' pauses for .01s each time you call it to ensure that it uses a new seed that's different than the last time you called it. That's why it's slowing down your code.
