@ Steve > The CDJ 2000's use "HID" mode with Traktor when connected via USB. Since Traktor does not have "Advanced HID" mode, this causes a lot of lag with the software, and even if your computer is brand new there will still most likely be lag.
How do you have your players and mixer connected to your computer?
Are you using USB cables from your CDJ's or are you using a Traktor sound card and the timecode CD's provided?
Sorry no one replied to you earlier, but I'll try to help you out as much as I can.