Slic3r PE and Prusa MK2s custom supports weirdness  

Slic3r PE and Prusa MK2s custom supports weirdness

Hi,

I'm using the Prusa MK2s and Slic3r PE. In the attempt to optimize my prints, I tried to model my supports manually, where there were overhangs. All of my supports grow from the model, are are "towers" with a C-shaped floorplan and a wall thickness of 0.15mm, which was also the layer height.
Now I was amazed at how great a job they did on keeping the bridges and overhangs up, while wasting only tiny amounts of material and being super easy to remove, but the rest of the model seems to have suffered a bit, and I have the suspicion, it might have to do with these supports.
Every time the printer got to printing the supports, it went on and tried to print some weird Infill structure through the whole model, while not really extruding filament, but while it got through all the weird movements, parts of molten filament were dripping out of the nozzle, catching onto parts of the model, where they should't. Then, when it was time to start the next line of filament at the correct place, the model suffered some underextrusion at the start of the line, until partially empty nozzle was once again filled with filament coming from above.

Now these extra movements weren't just some funny jumps, they were tracing those honeycomb/diagonal shapes typical for infill.
When looking over the gcode in www.gcode.ws, there doesn't seem to be any indication, that these movements were part of the gcode.
Has anyone else encountered a similar behavior?
Thanks in advance.
Cheers,
Ivan