Thanks Eric! I noticed some odd artifacting on a youtube video the other day which I'm assuming is the RAM issue you warned me about. I'll try scaling back the RAM a bit more and see if it happens again. It may have just been a fluke, but I'm glad you gave me a heads up on what to check first.
The bit rates on AVCHD explain a lot because that matches pretty closely to what my max hard drive usage was. I try to keep all my video files on an SSD, but that is starting to run out of space. I just need to wrap up a few projects so I can archive them on my backup drives. It sounds like a larger SSD would be useful anyway though so I never have to store my media files on my HDD (which I occasionally do now).
I also found this image on the tweakers page that cc merchant linked that shows AVCHD being at the bottom of the disk intensity scale. I also use GoPro footage so this chart gives me an idea of where that stands too. 
I just have one last question then. I noticed that the tweakers page is all about optimization for Premiere Pro. Does the disk optimization apply "apples to apples" with After Effects? If it does I'll just go through the tweakers page and set things up accordingly. Thanks again for all the help!