Hello Doug,
The suggestions for Windows tweaks in our own document (
http://www.hauptwerk.com/clientuploads/documentation/Tutorials/WindowsOptimizationsAndDiagnostics.pdf ) reflect what I've found to work best specifically for Hauptwerk on my own computers, and based on feedback from Hauptwerk users. They aren't necessarily definitive, and you'll inevitably find different, and probably occasionally contradicting, recommendations elsewhere around the Internet. Each PC is potentially different (often a unique combination of many hardware and software components, all made by different companies), and people use PCs for different things, and in different ways. Also bear in mind that there might sometimes be differences between what could benefit Hauptwerk use most, and what could benefit general 'pro audio' recording studio use (D.A.W.s -- Cubase/Logic/Pro Tools/Sonar/Reaper/etc.) most.
For example, being able to stream large amounts of audio data to/from disks/SSDs reliably in real-time at low latencies would normally be important for very D.A.W. use, but it doesn't matter at all for Hauptwerk use. Likewise D.A.W.s usually need to run lots of small separate plug-ins simultaneously, rather than devoting as much of the available computing resources as possible to a single intensive task (Hauptwerk).
By all means feel free to experiment with different Windows tweaks, but do bear in mind that whilst some might improve performances in some cases for some uses, they might have the opposite effect in other cases and for other uses, so my advice would be to try each one, carefully testing relevant aspects of performance before and after making the change, and keep notes on what you've changed (in case you need to undo changes later).
With regard specifically to whether to set Windows' processor scheduling to favour 'Programs' or 'Background tasks', my understanding is that the former makes Windows give more priority (effectively more CPU time, but in smaller slices) to the foreground application (which would usually be Hauptwerk), whereas the latter makes it give more priority to background Windows tasks/services (
http://www.thewindowsclub.com/processor-scheduling-in-windows-7-8,
https://stackoverflow.com/questions/17944180/windows-service-performance-vs-windows-application-performance ). No parts of Hauptwerk run as a background service, so you'd probably effectively be taking some CPU time away from Hauptwerk with the latter setting, although longer time-slices might benefit benefit Hauptwerk's audio engine in other respects. By all means feel free to try each option, but do test and compare the results carefully (polyphony, resilience to audio glitches, MIDI latency, etc.).
Cantabile have an excellent (and very comprehensive) document on Windows audio performance tweaks too:
https://www.cantabilesoftware.com/glitchfree/?utm_source=mailinglist&utm_medium=email&utm_campaign=glitchfree1Hope that helps.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.