How to prepare a constant benchmark environment

There are many ways to do that - what I tend to do for my testing, is using WAIK (Windows Automated Installation Kit, available free of charge from Microsoft), to deploy a minimal windows 7 system on a separate workstation.

Then, the following configuration items need to be considered/changed (try not to deviate too much from a typical user machine, thou, otherwise your benchmark would not be constructive):

• Set Paging File to static 2x RAM
• Disable Automatic Updates
• Disable Drive Indexing

These represent a reasonably optimal environment for testing, that is still attainable by enthusiasts, and thus can be representative of a Power-User (even if I use Automatic Updates and Drive Indexing, I schedule them both for when I'm away/sleeping)

As for caches and memory usages - at least in Win7 Professional, you can script remote startup - so for instance, I would have a script run my benchmark overnight (for large regression tests), restarting the OS after each run. Or I would run the same benchmark 5-10 times without rebooting, to see if cache usage changes.

Finally, there are bootloader switches to control the number of processors and the amount of available RAM - my test machine is an AMD Phenom X6 with 16GB of RAM, but we need to test how performance changes with the number of cores (some users would have single-core systems, and some would have multi-core systems), and with the amount of RAM (from 1-16GB).

This is usually done prior to a checkpoint release, to see if recommended or minimal recommendation need to be adjusted due to both extra features and additional optimization that happened since.