speed up ISV

[kukelyk]

I am new to ISV. I have a very simplified machine model, and huge mold parts. I have to check collisions between many pairs like head and table, y-slide to table, etc, 7-8 pairs. I found when collision check is on, and some parameters varied, the simulation is much faster, then w/o collision check. I cannot understand it..
What setting are the best for fast simulation, with gouge check? What options makes it slow?
Thanks in advance

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kukelyk