A Since it gives you the speed you want, I just wanted to float the idea that you could use the High Performance plan, and adjust it to your needs.
Possible solution B
There are a lot of hidden power options that you can't see in the Power Options control panel.
I am guessing that the built in profiles toggle some of these on and off, and that one or more of them is causes the behavior you are experiencing.
You can view a list of the hidden settings here (this is for Windows 7, so there may be new ones in Windows 8).
From the command line, their usage is:
Powercfg -setacvalueindex scheme_current sub_processor [GUID] [VALUE]
And finally, to activate the plan:
Powercfg -setactive scheme_current
Here are some interesting ones:
Processor Performance Increase Policy
Descripion: Specifies how a target performance state is selected if the current processor utilization is above the value of the Processor Performance Increase Threshold setting.
2 - (Ideal, Single, Rocket)
Processor Performance Boost Policy
Descroption: Configures the processor performance boost policy. The behavior of this setting can differ between processor vendors and specific processor models. The processor vendor should be consulted before changing the value of this setting.
Allow Throttle States
Description: Specifies that the performance state algorithm can use any ACPI throttle states (T-states) that the system supports.
1 (No, Yes)
To understand the options in details and dependencies on other hidden options, see the doc or this image.
There's is also a document written for Server 2008 R2 which might have additional information, but I'm having trouble downloading more than the first 13 pages.