Reply to Audio interface

I am using my Numark DJ IO as an audio interface for production right now and either because of the soundcard or my laptop, i get huge cpu load alike delay, and lag on the DAW. Audio keeps cracking etc.

Laptop is Core2Duo 2.0 ghz with 4 gig ram etc, not super new but not that crappy as well. So is the audio interface is my problem, if so what are some good audio interfaces in below 0-300$ range?