When slicing models such as the nautilus gear from http://www.thingiverse.com/thing:27233, Slic3r produced many tool moves back and forth across the print which with materials that ooze, produce a very "dirty" print with a lot of material filling in spaces, almost impossible to manually clean. examples are Taulman's Nylon 618 and LAYWOO-D3. no amount of retraction or slow print speed can help this.
Use nearest-neighbor search for internal perimeters too. #1025
I've been meaning to fix that for a while, thank you for the reminder. Perimeters order should be much smarter now.
Here is what I mean http://www.youtube.com/watch?v=E4D9wVvIB7s