Thoughts on improving function execution time?

Matlab Community/Experts,

I was able to reduce the execution time of the attached function from about 120 hours down to about 2 1/2 hours with the use of "parfor" and vectorization.

Would be great to reduce execution time further without installing the parallelization tool box.

Does anyone have any thoughts/suggestion on how to further reduce exection time?

Spent a good part of the day digging through various similar answered quesitons though I am tapped out.

Also attached a snap-shot of my CPU performance at high and low utilization periods. I think that my laptop has the "capacity" to do more work though I do not know how to tweak it (without dipping into the parallel tool box).

Thank you,

CD