...one more tip, related to multiple passes... As the script is processing, you'll see the status area at the bottom updating...

Running Pass: X Repetition: Y...

...as it goes through each itteration (or Repetition).  For very loose Threshold values, the Repetition count may only go up to 20 - 40 or so and for tighter Threshold values, the count may go up to 100+ (or more - lots of variables determine how high, including how badly the mesh is mangled to start with).

"Generally", you might get the best results if that count drops down to the single-digits (or something approaching the Steps value), for a given Threshold value.  My suggestion is to experiment with the Passes value - run 3 or 10 passes at the same Threshold and see if that's better or worse than one pass.  It might start counting up to 100 or more on the first pass, then drop to 74, then 52, then 30, etc... in other words, each pass should (normally) affect (fine tune) fewer and fewer vertices. 

[The above comments are mostly related to small / dense polygon areas, using a small Threshold - remember that large polygons will move more and more towards the base shape with each pass]

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