What creates motion blur when recording ingame?

I need help with figuring out what it is that causes the motion blur/lag when you move the camera while recording in game. I have tried many different programs, many different codecs and many different settings, but I always get a type of lag when I move my camera. It's like the camera moves slower than the mouse as soon as I start recording. It's driving me nuts since I should have enough juice in this computer to make recording effortless. I see a lot of videos of the very same game, in more taxing situations that what I have been testing in and it's as smooth as ever.

My setup:

i5 2500k
HD 7950
6gb 1600mhz RAM
standard 7200rpm hdd


It's not the FPS dropping that causes the lag, I'm still at 150+ fps when recording at 1920x1080 on 2 monitors, both with a game client open. It's not the CPU or RAM either, CPU sits at 30-50% depending on how much is happening around me and RAM at around 80%.

Any ideas? I'm going a bit crazy here since I cannot figure out what the issue is.