I am playing Saint Rows on PC. ;) Most of my game recorded in Dxtory are super laggy except for the ones recorded with Dxtory Video Codec. My problem with that is the file it makes is 100% times larger compare to ones recorded with Lagarithm Lossless Codec. :'( I wish the dev could fix or come up with something I can use with SR games with no lags.
dxtory codec is pretty darn light, because it doesn't have much of compression. If you want smaller files, you need compression -> compression is cpu/gpu intensive operation.
Buuut, you might want to try magicyuv. It is quite similar to lagarith, but faster. You can get it here: http://magicyuv.com/index.php/download
The latest version is "pay what you want", you can "pay" zero amount if you wish, thus getting it free.
What mean laggy? You losing frames when record or just can not play in real time what was recorded? Have you enabled multitheading in codec? I propose UT Video it is free and losless like lagarith but use less resources. Lossless is only good for later editing, it is not good for playing, so just re-encode to h264 later.