This tweak is for those with mobile Athlon XP processors; it may work with other brand processors, but I was only able to test this with my mobile XP.
Windows often incorrectly detects the amount of L2 cache on the processor, which may slightly hamper performance. To do this tweak, you are going to need CPU-Z which can be downloaded for free from here.
Open up cpuz.exe and look for the cache section on the CPU tab (default selected), and note the number beside "Level 2".
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Open up regedit by clicking start, run, and typing "regedit" into the text box.
Navigate to HKEY_LOCAL_MACHINE\STSTEM\ControlSet001\Control\Session Manager\Memory Management
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Double click on "SecondLevelDataCache"
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Type one of the following values into the text box according to the value presented by CPU-Z in DECIMAL form
256 KBytes = 0
512 KBytes = 200
1024 KBytes = 400
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Click OK, exit regedit and restart your computer.