I just reformatted this machine with a particular focus on latency. I need to put together a more readable list of things, but in short: I did disable core parking right away, turbo mode/speed step/HPET were all "immaterial" to items that jack latency through the roof in the system, OC increases heat and induces page faults (as well as dielectric breakdown of the CPU) so have never used this. Power options to idle/sleep nothing are also important (run through the entire list in the "advanced power settings" pop-up).
The biggest hitters to latency are "automatic [anythings]" with Windows Search (disabled in "services.msc") and network auto discoveries (in Control Panel\All Control Panel Items\Network and Sharing Center->"Change advanced sharing settings") being # 1 and #2. Both of those are very aggressive and self-starting unless specifically disabled. I even brought this back online with Avast 2015 (in "Silent/Gaming Mode"). Highest page faults come from Internet Explorer, not surprising really, but the system can be online (was in the forums at the time), SONAR open (transport was not running during this capture), Avast running, and looks like this:
Depending on Internet Explorer usage the total reported fault count (bottom bar) will ramp up into the red.
The other big picture item is to monitor "msconfig.exe," both services and startup tabs for non-essentials (many programs will load themselves into boot just by starting them). Hardware support/virus protection are essentials (not recommended to disable those).