Changing CPU frequency policies in OS X
Run the command top in the Terminal. This will tell you where all your CPU and/or memory is going in more detail than activity monitor (man top to learn more about it). My immediate assumption is that your CPU isn't maxing out because it has no reason to. The default power management by both Apple and Intel does its job very well; I would guess you get this slow tab switching when you have lots of applications open, or a few very large ones. 

If your Mac is taking time to compress and expand memory, it will run slower. If (heaven forbid) you have actually used more memory than you have physical RAM, your MacBook is dumping dynamic data to the hard drive. This will run SUPER slow, but use relatively few clock cycles.