The first step is go here and do these..
This is a copy & pasts of an old old post of mine.. Its 2k need to update for XP
(Xp will have about double processes running than whats shown here)
A computer used for Kj, DJ, or recording should not have many background applications running. The processes for normal computer operation should be at a minimum. To check these out ---> cntrl+alt+del then click on task manager.. Below is a Win2k Pro just after boot and shows a normal list of the procs running ( should be about 20) which is listed lower left. Do a Google search on suspect procs running to find out their functions and whether or not they should even be running.
Notice the CPU usage at 0% ( nothing running in background ) When first setting up a computer or big file change ( defrag etc ) the Mem Usage should be noted to gauge when the hard drive is running out of memory. When virtual memory or resources are low it causes dropouts and glitches in the audio. Do a disc cleanup on a regular basis and defrag depending on amount of usage.
Next is the same with Sonar 3 launched but idling. When playing or recording the cpu usage will have to be read in Sonar which takes control of cpu ( 100% ) but shares with other applications as they need it
Check cpu usage with whatever programs you run then if problems arise you have an indication of something hogging cpu cycles.
With a little bit of experience one should know if his computer is still perkin along like it should be...
For real tweaking one can go into services in cntrl panel-->admi-->serceces and dble click on any service set it for auto man or stop or start it..
Then I like Jerry's link here