@giuseppebufalo I will get back to working on performance when I am closer to certain that the functionality is working perfectly. Right now it is not. I will try to look at the show_in_editmode thing soon, since it is likely to be easy to fix.
@chippwalters You are not the first to ask for this, so it is something I will consider. The code for 2D intersection is there. I would just have to do a 2D inside/outside test and then hook this up to the code. I was thinking: if I detect that all the meshes are in the same plane, then just do a 2D boolean instead. But I need to make sure the 3D boolean is as good as I can make it before adding new functionality like this.