Basically, “Ultimate Performance Mode” makes sure the OS is running the “Always On” powerscheme. That´s more or less it.
Just set it up this way yourself and save a few bucks on a less expensive version of windows.
Preliminary results suggests that the overall performance gain is negligible. However, the goal was really to reduce micro-latency so a real-time audio process could potentially benefit from reduced drop-outs etc. Again, just change your power scheme.