Both Constructs have always just used an axis-aligned bounding box test to test very quickly if there's no collision (4 number comparisons), then a bounding quad intersection (2 quad intersection), then the full collision poly intersection check. I've been meaning to add some kind of system to reduce the number of comparisons that need to be made, but to be honest, for 2D games the axis-aligned box test is so fast and discards almost all candidates so quickly that I've not felt there's a pressing need for it. You really need thousands of objects before it slows down as it is, and if you use tiled backgrounds properly, you're unlikely to reach that object count.