Microsoft recently caught my attention with the release of a performance-related hotfix. Blog readers should pay attention to KB2555428. It fixes an issue which can cause Windows 7 to boot extremely slowly. The culprit is System Restore with the slowdown occuring when many restore points have been created.
To quote Microsoft Support on the symptoms you’ll experience:
“Consider the following scenario:
You have a large hard disk installed in a computer that is running Windows 7.
You create many restore points on the computer.
You try to start the computer.
Given this scenario, startup time may be very slow.”
Unfortunately, Microsoft does not give a specific number of how many restore points actually lead to this issue, so it may vary from PC to PC.
Each restore point creates a snapshot that needs to be validated by “Volsnap.sys” during bootup. This is where the problem occurs. Once restore points exceed a certain number, ReadyBoot stops working properly because too many snapshots need to be validated. ReadyBoot, which is related to ReadyBoost, is a Windows 7 feature that improves startup times by pre-caching startup I/O operations—to do so, it needs a boot plan featuring the most commonly used system files.
However, due to a large number of restore points and snapshots, the boot plan will grow above the size limit of 512 KB, prevent ReadyBoot from functioning, and cause a slowdown in boot performance.
My first piece of advice: get rid of older System Restore points you no longer need. The easiest way to do that is to run TuneUp Utilities 2011. Once installed, go to “Gain Disk Space” and click “Old backups”.
Check “Old restore points” and hit “Clean” to delete all of the restore points, except for the most recently created ones. This will clear things up.
Note that Microsoft also created a hotfix that tackles this issue. It is available only from TheHotfixShare (see 32-bit hotfix download and 64-bit hotfix download). Please note that hotfixes are experimental updates that Microsoft pushes out to solve critical customer problems. They’ll eventually end up on Windows Update or as part of Windows 7 Service Pack 2. If you’ve experienced this issue and don’t want to delete any of your restore points, this fix will help you.