Partitioning the problem is a really cool idea, especially since it shows how to easily split up the processing (if only I could). Also I appreciate your code. When I plugged it into my program, it wasn't faster than my starting point. I am guessing it would be faster if my list was larger than 10,000, or if I had a computer with many processors running the algorithm in parallel. At the current size of my list (slightly less than 4,000) the current optimization is the fastest. Just as an FYI, with all the stimulating ideas that were shared, I managed to improve the speed by more than 47 percent.