When you enable faster launching for a Windows AMI, images are pre-provisioned, using snapshots to launch instances up to 65% faster. To create the optimized Windows image, Amazon EC2 launches an instance and runs through Sysprep steps, rebooting as required. Then it creates a set of reserved snapshots that are used for subsequent launches. The reserved snapshots are automatically replenished as they are used, depending on your settings for launch frequency.

To change these settings, you must own the AMI.