If it wasnt the fake SMBIOS that was causing the problem, our next thought was to look at the AppleIntelCPUPowerManagement.kext hack. This kernel extension is disabled on all Hackintosh installations including so-called vanilla installations by either by removing the file itself, or adding another file to disable this feature. Once we re-enabled the kext, things returned to normal speeds. Deleting the file completely resulted in slower speeds once again.
With such a performance hit when running a hacked Macintosh, the Apple Tax takes on new meaning. Other notebooks may have similar performance penalties due to power management idiosyncrasies--the difference was never noticed because no one tried creating a Hacked Mac on a Mac.