Point generator slow

[MorganAskins]

For some reason the point generator takes around x10 longer than it should in comparison to the fill generator when simulating events. Naively it should be faster than the fill generator since it doesn't have to do any geometry guessing. One can also create arbitrary volumes to fill and as you decrease the volume down to point-like sizes it approaches the point generator speeds.

[tgrbrooks]

I've had a bit of a look into this and I don't think it's the point generator itself that's at fault, it seems to be more of a geometry/light propagation issue.
If you generate points near the PMTs (e.g 0, 0, 6000) the speed is more like what's expected (~2s per event) and then it slows down as you get closer to the center of the detector.
Still probably a bug somewhere, but likely deep in the light propagation code...
(However I don't know how this fits with Morgan's observation of the speed decreasing only when filling an area of around 1 cm as the point generator takes about 25 s per event at 0, 0, 3000 so maybe there is more than one issue)