We have been reporting for the past few months on a long-standing bug in Windows XP that causes SVCHOST to push the CPU of a PC up to 100 percent usage. Microsoft was supposed to finally fix this issue with a patch that was released in November, but the update failed in this goal.
With official support for Windows XP due to end in less than four months, there's very little time for Microsoft to fix this problem for the many users of the 12-year old operating system. A few days ago, Doug Neal, the senior program manager for Windows and Microsoft Update, sent out a message to the subscribers of the PatchManagement listserv. He stated that Microsoft has found what was causing SVCHOST to increase a PC's CPU usage:
From the extended Windows Update logs, we saw the issue stemmed from inefficiencies in the Windows Update Agent processing long lists of superseded updates. And the problem was exponential in that each additional superseded item took twice as long as the previous item to evaluate. With lists as long as 40+ superseded items, the processing cost on SVCHOST via the Windows Update Agent had an exceptional impact on client PCs.
Neal said that Microsoft tried to get rid of a large number of superseded updates in the IE6 and IE7 lists in order to fix the SVCHOST issue. Unfortunately, the updates to Windows XP released in November, and also earlier in December, failed to squash this bug. He stated, "We're working diligently to release changes to the supersedence logic that will comprehensively solve this problem. It's a top priority. And the right (and smartest) people are on it."
He added " ... we're working through the holiday to provide the right fix as soon as possible. As you can imagine, we don't have an ETA. And we want to make sure the next fix is the last and comprehensively solves this for our customers."