KB2510636 - An update that improves the startup performance of Windows 7 and of Windows Server 2008 R2 is available
You have a large hard disk installed a computer that is running Windows 7.
You create many restore points on the computer.
You try to start the computer.
In this scenario, the startup process may be very slow.
This issue occurs because the boot plan for the ReadyBoot feature exceeds the size limit of 512 kilobytes (KB). Each restore point creates a snapshot of Windows that Volsnap.sys must validate during the startup process. When you create many restore points, the boot plan for the ReadyBoot feature eventually exceeds the size limit of 512 KB, and cannot be stored. Therefore, startup I/O operations are not precached, and the startup process is slow.
Note The boot plan is stored in the following registry entry: