Thanks for the reply. Ya, I found a couple of different libraries in the meantime, but like you said, 90% of them use AVR assembly for speed. I did however run into this:
http://arduino.cc/forum/index.php/topic,140107.0.html
Apparently we have access to an almost complete CMSIS/DSP_Lib, you just have to follow the instructions above to be able to access it. For what I need to do it's working pretty well, but definitely check that library out, it's got a ton of useful functions in it.