Is your Windows XP system slower than it used to be? Despite performance-optimizing features, such as the application prefetching feature (which lets XP cache frequently used applications), over time your XP system can lose the zip it once had. But if you tweak a few settings and periodically do a bit of housecleaning, your system will regain much of its original speed. Here are 10 tips for optimizing the performance of your XP desktop.

10. Defragment your hard disks—Even if you have a fresh installation of XP, you should regularly defragment all your system's physical hard disks. To run the system defragmenter, use the defrag command or run dfrg.msc. I recommend doing so at least once a month—more often if possible.

9. Periodically clear the Prefetch folder—Found at %Windows%\prefetch, the prefetch folder contains pointers that help the system load programs that you've recently run. Over time, the accumulation of little-used entries can degrade system performance. Empty this folder about once a month; cleaning it out much more often will degrade performance.

8. Disable unneeded services—By default, XP installs services that many users don't need. Disabling unnecessary services makes the resources that they used available to other applications. You can use the Msconfig utility's Services tab to disable services. For a list of services that can often be turned off, see Top 10, "Unneeded Services in Windows XP," December 2003, InstantDoc ID 40722.

7. Get rid of unneeded Startup programs—Programs that automatically install icons in the system tray and Startup folder are one of my pet peeves. Although they usually add no functionality, they do eat away at system resources. To get rid of these parasites, run Msconfig, click the Startup tab, and clear the check box for each program you want to disable.

6. Adjust the Visual Effects setting—For systems that don't have a lot of CPU power (less than 800MHz), you can boost screen performance by changing the Visual Effects settings. Open the Control Panel System applet, click the Advanced tab, click the Settings button in the Performance area, then select the Adjust for best performance option.

5. Preset the paging file size—When your system needs more memory than it has, Windows expands the paging file and all other system functions stop until the expansion is complete. Setting the maximum paging file size to twice the amount of physical RAM typically lets you avoid that performance hit. Open the System applet, select the Advanced tab, and click the Settings button under Performance. In the Performance Options window, select the Advanced tab, then click Change under Virtual memory. Enter the desired maximum paging file size in the Maximum size field.

4. Get a second hard disk—With today's multigigahertz systems, the performance bottleneck is almost always the I/O subsystem. Spreading I/O over multiple hard disks relieves that choke point. Put your OS on one drive and your applications on the other. Adding a drive also helps you keep the recommended 20 percent free space on your system drive.

3. Use the DMA setting for all your hard disks—When you add a second hard disk, XP often automatically sets it to the slowest Programmed I/O (PIO) mode. Most of today's drives are capable of using the far more efficient direct memory access (DMA) setting. To change the drive settings, open the System applet, click the Hardware tab, then click Device Manager. Expand IDE ATA/ATAPI controllers and open the properties of the Primary IDE Channel. Select the Advanced Settings tab, and select DMA if available from the Transfer Mode drop-down list under both Device 0 and Device 1.

2. Paging File Location—If you use a two-drive system, you can enhance performance by moving the paging file I/O to a different disk spindle than the one the OS uses. To do so, open the System applet, select the Advanced tab, and click the Settings button under Performance. Select the Advanced tab in the new window, click Change under Virtual memory, and select your system's second drive from the Drive list.

1. Get more RAM—Getting an adequate amount of RAM is the most effective way to improve XP's performance. If you don't have enough RAM, no amount of tweaking will make your system run faster. Every XP system should have a minimum of 256MB of RAM. For power users, 512MB is even better.