If multiple programs finish recording at around the same time, their commercial detection jobs are serialized. Would it be possible to parallelize them?
There is an option to specify the number of threads to use for commercial detection by providing your own comskip.ini. Therein, you can specify to use as many threads as your CPU can handle.
While this does not parallelize the running jobs, it does allocate more resources to them, so they finish more quickly.
Nice thought, but makes we wonder...
Realizing that by default comskip takes a thread/core to do it's work and is processor intensive, don't think parallelization or a GPU would help since it has to do (sometimes multiple) serialized passes through the media.
Most Channels DVR users don't have the resources on their Mac/PC/NAS/Pi/whatever lowestcost hardware/etc they use for that.
Personally, I use a custom comskip.ini to give it two threads and it eats 50% CPU on either of my NAS's doing it which works for me.
All depends on your use case/workflow. If everything was done in parallel, my workflow would change dramatically (for the better if I had the resources) and would have to be re-written.
So when it's all re-compiled/re-written for the new Quantum Computers coming out next year... I'm sure we'll be discussing it 
P.S. Sorry, just had to add that reference to Quantum Computing next year, since I may be accepting it as Sci-Fi reality instead of laughing about it then. One never knows, but can have fun while trying to...