Hello!
Not to be Captain Obvious, but are you concerned that your CPU is not grinding (working hard) or concerned that the tasks are now taking a lot longer.
If the tasks are not taking longer, don't expect your CPU to be working hard either, especially with a 64-bit process and the monster machine you have it on.
I know your feeling, my laptop, (minor equipment) will lag, grind, and take a bit longer to run processes and I can watch the CPU usage spike. My base computer (built just a wee bit hardier) doesn't even blink an eye for CPU usage, and my processing time is much faster.
Then there are times when both machines just seem to take forever. Sometimes processing in ArcGIS is time consuming and it seems like there is nothing we can do to make it faster, including building a computer to rival NASA. We just need to be patient and hope that ESRI continues to improve their ArcGIS software.