If you have been recently affected by a slow-down of your XP PC (like suddenly you feel that it takes longer to open a program, to boot etc.), you are not alone.
Apparently, Microsoft's Patch for Windows XP - 811493 slows down your computer... a lot. Here are some articles on neowin and USENET discussions.
I had the same problem. The way to fix it is - to uninstall the patch from Control Panel -> Add/Remove Programs. After I did that, the PC was back to what it was. I could not find an official reference to this problem from MS TechNet. I would post it if I find one.
When did we get into this patching frenzy? If I understand this patch (Service Packs, Critical Updates etc) process correctly its like the company selling you the software saying, "Hello customer, here's our product for $499, which by the way, we have not completed fully, and which would certainly have a lots of bugs. Enjoy..... And, we may get to completing the product at our convenience and it is upto you to get the new so-called patches.... Thank You"
Well, we poor customers have no choice, it seems!
Latest Info from Microsoft: Microsoft originally issued this patch on April 16, 2003. Subsequent to that date, Microsoft has received reports of performance problems with the patch from some Windows XP customers. Microsoft has investigated this issue and confirmed that there can be performance problems when the patch is applied to Windows XP Service Pack 1 systems. Microsoft is actively working on a revised patch for Windows XP Service Pack 1 and will re-issue that patch when it has been completed and fully tested. The existing Windows XP SP1 patch does address the security vulnerability.