Might not be processor intensive . . . yet it sure takes 10-15 seconds to calculate after a new number is input.  Ten years ago, the calculation after a new number is input was virtually instant.  The program takes well over a minute load and be ready to use (start-up time after clicking the icon), and easily fifteen seconds to open a client once one is selected.  And the computer I'm using today is far more powerful than the one I was using 10 years ago.  The processor is an i5-6400T, not the fastest by today's standards, yet not a slouch, either . . . ought to be running simple calculations instantly.  And the system is running 16GB ram, so there's no possibility of a bottleneck.