Change XP to the Classic theme: Right-click on the desktop and select Properties. On the Theme tab, select ‘Windows Classic’ from the drop-down menu. Click Apply, then OK.
On systems that use shared system memory for video instead of dedicated video memory, turn off the wallpaper and reduce the color depth to 16-bit.
Reduce visual effects: Right-click on My Computer and select Properties. Click the Advanced tab. Under ‘Performance’, click Settings. Select ‘Adjust for best performance’. Click Apply, then OK, then OK again.
Open the Registry. Start > Run > regedit.
Go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\PriorityControl
Give ‘Win32PrioritySeparation’ a Hex value of 26. This prioritizes applications over background services. Do NOT do this on a server.
Go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
Give ‘DisablePagingExecutive’ and ‘LargeSystemCache’ each a value of 1. The first one keeps critical OS and application processes in RAM and prevents them from being written to the swap file. This keeps apps more responsive. The second one makes that RAM cache larger. This does not reduce swap file use per se, but it does keep the more important stuff in RAM so apps remain (mostly) immediately usable.
Close the Registry.
Schedule weekly disk defrags: Open a command prompt. Enter: at 03:00 /every:Sunday “defrag c:”. This will defragment the C: drive every Sunday at 3:00am. Change time and day values to whatever you need. Enter a separate ‘at’ command for every local drive letter, staggering the times by 30-60 minutes.
Reboot and enjoy. It won’t be greased lightning, but it’ll be better.