Which usually means that your CPU was running a lot slower, and possibly very hot too. I had the same problem, but I'm not using MC's legacy kext – the Geekbench score dropped on the HP from 4040 to a low 1600 and was running very hot.
And you used "Safe Boot" like IOPlatformPluginFamily.kext and ACPI_SMC_PlatformPlugin.kext? Now try Safe Boot (-x) mode
Not really. It didn't affect the functionality or the performance as far as the Geekbench scores and temperature are concerned. Most of the time, it delayed the boot. Actually, my temperatures values, which are floating between 46-55 on load, are almost the same with or without Legacy ACPI_SMC_PlatformPlugin, especially after the most recent version of AnVaL.
For a very long time I had MacbookPro5,4 as my mac model but with the new features of AnVaL, I have to use MacbookPro5,5 as otherwise I lose stability. Also, I used SMbiosproduct key to override motherboard of the mac model, which increased my Geekbench score alongside with a surprise by Apple offering me efi firmware upgrade (: This showed me that putting just mac model to smbios.plist might not be enough.
I can't speak with a scientific mind but all I can say about this CPU thing is that while using OSX on battery mode, it seems to me that CPU can goes into deeper states than it does on AC Power. So, I think although I have C-States working I doubt that I have all of them enabled.