Slic3r top layer issues, small gaps, weird extruder paths
To have a very smooth finish on top layer, I usually act on these settings :

in Print Settings :

Layers &amp; Perimeters :
  Horizontal shells : 3 / 3

Infill:
  Infill, Top/bottom fill patterns : Archimedean Chords ;

Speed:
  .for print moves :
   Top solid infill : 20  (mm/s)

Advanced:
  Extrusion width, Top solid infill : 0.2 (mm)


= This gives very slow movement in a circular way, the small extrusion creates an ironing effect, thus very nice finish.

Considering your slicer behavior, have you tried changing number of top shelves &amp; Infill type ?