Well, as this script is meant primarily for animating chains, I have not payed much attention to how the chain is created in the initial stage. You could try to rebuild the curve uniform before running the script...

Internally the script works something like this:
- create a straight duplicate with equal length of the original curve.
- create the chain links along the straight curve (easier this way) and point constrain them to each other
- hook up the controlling and dynamic stuff
- move the CVs (actually the control cubes) of the straight curve to match the original curve. This moves the chain links too as they are connected to the curve

If the initial curve is funky and the span lengths are varying, the chain will look odd. But if you hit play, the chain settles down after a while as the spring forces even out. If you're happy with this "pose" you can stop the animation and select Solvers > Initial State > Set For All Dynamic. Now when you hit rewind the chain will keep it's "pose" until you hit play again.

The "Optimize rigid solver" turns off the friction and bounciness calculations of the rigid solver node. I'm not sure how much these actually affects the animation performance (my thought was "why have them on if they're not needed...")