SP1 Slowdown Hotfix
The mandatory roll out of SP2 on April 12, 2005 makes this update officially obsolete. It is highly recommended that you install SP2. This Hotfix is included in SP2 and is being kept up for those who refuse to install SP2 at this time. If you have installed SP2 do not install this Hotfix.
SP1 Slowdown Hotfix - Download - KB815411
"Heap Algorithm Update for Atypically Large Heap Requests" originally titled "Programs Run Slower After You Install Windows XP SP-1" fixes a flaw in Windows XP SP1 memory handling code. Here is Proof of what Microsoft posted in their original article:
"Changes to memory handling code result in programs which often allocate memory (which is many of them) can take up to ten times longer than normal to start."
Instructions - Install this update after installing SP1.
Update - Microsoft updated their KB article (and continues to update it) to try and dismiss this issue as only affecting select users and one application that Microsoft has tested "internally".
"This fix in the Windows XP Service Pack 1 (SP1) and Windows Server 2003 heap algorithm was released to better handle a particular atypical and uncommon sequence of heap requests by a private, internally developed program that is not commercially available."
Since it is common logic that Microsoft cannot possibly test EVERY Windows application in existence and there is always a possibility you are using one or many such applications that do not allocate memory the Microsoft way, I would recommend installing this Hotfix. I'm not sure how you confuse many applications with one that is not commercially available? The updated article goes on to say:
"It is not recommended that you use this fix except to address the specific program."
Yet this Hotfix is included in SP2? Why is this "specific" Hotfix included in a service pack if it is unnecessary? Regardless, numerous people including myself have noticed a speed improvement after installing this Hotfix.