So, I've been doing a lot of my Drupal development at work on Windows XP. For some reason Drupal was running extremly slow. After searching off and on for a few days, I finally stumbled across the right key words to find this: http://drupal.org/node/348202
Solution: increase realpath_cache_size in php.ini to something larger. I set it to 20M. I might make it bigger, we'll see. But at least Drupal is usable for now.
Oh, and I should note that when I am developing on Linux or on my server, Drupal is plenty fast. So this was a problem specific to my WAMP install.