DescentBB

A little known Windows 7 feature will allow you to speed up your boot time by taking advantage of these advanced hardware configurations.
Launch the Start menu search bar and type msconfig. Select the Boot tab. Click on Advanced options and set the number of processors from 2 to 4, of course dependent upon your systems hardware. Select 2 for a dual core processor and 4 for quad core.

http://www.trainsignaltraining.com/wind ... more-12806

that switch is actually for limiting the number of processors windows uses. Been there as long as msconfig has been in.

the first comment on that page notes that, and points to a Microsoft KB article about it.