I love your explanation of how it works, but to answer your question you can use gpupdate /force from the command line should allow any "policies" or registry changes you make during the instance of windows to take effect, you could probably make the change use gpupdate /force then do a benchmark.. then change the value and run gpupdate /force and it should give you comparison values to make your decision from.

Another easy way is to simply log off and then log back on... but I'm never one to do things the easy way.