Hello Rick!
The problem seems to be with the document, not the script. On a test document i made, on my much inferior system, it only takes about 10-15 seconds.
Things you could try:
1) before running the script do a File->Save As.. so you collapse the undo stack (one of the biggest performance hogs for indesign).
2) If you have text variables, nested or grep styles, it's almost certain they are causing the slowdown. With Grep Styles, the performance hit increases more than exponentialy with the number of them (in the test i did with your script, adding 5 grep styles, on about 20 paragraphs scattered in the document increased the runtime of the script to almost 1 minute).
3) In some cases large tables create a noticeable performance drop, and also anchored objects, above a certain limit i did not found yet.