Change Processor Scheduling settings

If you’re troubleshooting something more than sluggish screen redraws, you’ll need to adjust the performance options on the Advanced tab of the Performance Options dialog box. There are three sections on this tab: Processor Scheduling, Memory Usage, and Virtual Memory. The settings in these sections have a major impact on how your system operates.
The Processor Scheduling section controls how much processor time Windows XP devotes to a program or process. The processor has a finite amount of resources to divide among the various applications. Choosing the Programs option will devote the most processor time to the program running in the foreground. Choosing Background Services allocates equal processor time to all running services, which can include print jobs and other applications running in the background. If your users complain about slow-running programs, you could try setting the processor scheduling to Programs.
On the flip side, if users complain that print jobs never print or are slow to print, or if they run a macro in one application while working in another, you may want to assign equal time slices (called quanta) to each process by choosing the Background Services option. If you use the Windows XP machine as a server, you’re better off choosing the Background Services option.