I have successfully upgraded to occ 6.9.0 and everything looks good and much improved in the boolean area. This multople boolean ops is a really nice feature. I have though experienced one bigish problem with cylinders cutting cylinders.
It appears that they are incredibly slow in some circumstances. It seems to be related to the resolution of the steps in IntCyCyTrim. Basically for my models the code which increments anU1 only increments it by a very small amount (~0.003) each time as aMinUexp is always small.
There is a while look at 2368
which is looped sometimes thousands of times for simple cylinders
I have run the same ops on 6.5.4 and all runs as expected, attached are the two cylinders I am trying to cut from each other
It is a bit out of my depth to fix, does anyone have suggestions?