Initial shutdown time on test machine: 32 seconds
1. Reduce Timeout To Kill Service Or Applications:
Before Windows shuts down, it attempts to properly close all running processes. If a service doesn’t close immediately, Windows waits for a few seconds, until it prompts the user that the service is not responding to the shutdown request. The amount of this waiting time is defined by registry keys and you can reduce it.
These are two fairly harmless registry hacks. If you follow the steps outlined in this article, it should in no way harm your system.
tnt advice: Editing the registry can damage your operating system! Make a backup of your registry before continuing.