Here is a great link I'd like to pass on for guys looking to record some great video in Planetside 2 and BF3! I won't reiterate too much because the video pretty much speaks for itself. Basically using this guys method to record, you can get excellent quality at the smallest file size possible. The links to download the software are inside the Youtube Video's More Info section
I wanted to add it did not record better than Fraps. However, for some reason the Codecs broke my Windows Media Player. I had to disable it and install VLC ( which is fine). It gave me the dreaded BEX error on everything.
Did you set it to record with absolutely no video/audio compression? Any compression at record time would bog down your CPU. Sorry to hear it's causing you problems, what OS are you using?