Comparison of perimeter crossing travel moves (with avoid crossing perimeters checked). The first is Cura (v3), and the last is Slic3r PE (v1.40). Neither is perfect in limiting perimeter crosses on the interior cavity of my part, but Cura is clearly better for prevention of stringing in interior cavities. The middle one shows Slic3r in vase mode where the only perimeter crosses are in the base layers.
Slic3r has a flag not to cross perimeters, not sure you’re using it.
@Miguel_Sanchez that box is checked in Slic3r. I suspect the algorithm invoked only applies to external perimeters.
Cura has 3 options for perimeter crossing.
In general I prefer Slic3r PE because of the extra options for infill, but it’s really annoying when you tell it not to cross perimeters and it still does.