I've heard using a secondary drive (not the one the game is running off) to save the video to helps increase performance. Never tried it myself, because I don't get much lag from recorders I use, but it would make sense, seeing as video recording involves a lot of constant writing to disk, and splitting the load of loading the game and writing the video onto different hard drives should help. Mind you if your computer isn't fast enough to record at a decent frame rate the diffrence really won't matter that much anyway.
Also, I've heard Fraps runs really well in terms of performance. When I record data I use the free MSI Afterburner (Normally a GPU overclocking program), which has a built in video recording function that works really well in my experience. Idk if the recording studio works on a non-MSI brand video card though, you'd have to try it first. (I don't think MSI itself made the program, I think it was 3rd party, so I'd suggest just trying)
And CPU, recorders chew up a lot of processes.