There is tons of stuff you can do yourself. My professional advice is to stay away from the Windows registry unless you're trying to resolve a specific problem (such as stubborn malware, software that won't install or uninstall, etc).
What is your purpose for needing to optimise registry performance? Do you just need to make your computer faster?
Here are my basic, quick and dirty steps to get your machine running smoothly. Windows XP is assumed here.
- Run msconfig and kill everything which starts up with Windows (leave antivirus and any vendor-specific apps that might be needed such as for hotkeys, temp sensors, printers, etc). If you need help figuring out what to disable, send me a list of your startup entries and I'll help you decipher it.
- Turn off the XP "eye candy". While not as resource-hoggish as Vista's effects, you will see a noticeable speed increase when the theme is set back to Windows Classic. Just go into the System control panel applet and to the Advanced tab, then click Settings under the Performance category. Choose the option optimised for performance.
- Set your page file to a fixed size or just disable it completely. I say if you have more than 2GB of RAM and never come close to using it, just disable it altogether... that's how I ran mine even when I only had 1.5GB. If you have a small amount of RAM or constantly fill it up, just set your page file to a fixed size of, say, 2000mb, or 1500mb or something like that. There are always mixed opinions about page file sizes, but I find it the size doesn't really matter too much. This is also located in the same dialog box as the above performance settings - just go to the Advanced tab and click the Change button.
- Disable System Restore. It creates lots of overhead and just backs up the viruses and spyware anyway.
- Clean up those temp files - Start>Run and type %temp% - and delete the contents. Then, Start>Run and type temp and delete the contents. I also recommend two free apps called DustBuster and CCleaner (just google them).
- Uninstall any toolbars and other dumb stuff that clogs up your web browser.
- Use Firefox, Safari, Chrome, and/or Opera for your Web browser. IE sucks hardcore (just run the ACID3 test and compare results). You also won't get the spyware in the other browsers, especially if you use something like AdBlock Plus.
- Defrag your HDD(s). I recommend a small free app called JKDefrag. Just google it or you can find it on the Hiren's disc.
There's a lot I'm leaving out but that should get you started. You gave me a good idea - I think I'm going to start a how-to for Windows XP performance.
Just let me know if you have any questions.