Printing vases seem to have an odd problem on my Kossel Mini - there are tight corners in which the print head movement is very fast. It causes thin strands to form. I'm using Slic3r. The only setting that seems to make sense in terms of speed settings is "travel" (speed for non-print moves). But the vase still has material that should be in these locations.

Thoughts on how to correct this? Photo attached of the outcome.

I've seen that too, both with my Kossel and my first cartesian (Makibox) So that's two differnt firmwares and styles ofprinter doing the same thing... I thought it might be something to do with the slicer crossing some sort of threshold (overhang angle?) and switching to bridge mode. I've never actually got round to investigating properly though.

I have had this too. It appears to be a fault in Slic3r's spiral vase mode. I re-sliced in Cura and the print was fine.

Yep, Cura took care of it. Frankly the Cura print is gorgeous....

Slic3r is probably detecting that as a bridge and traveling at whatever your bridge settings are. I think there's a setting for turning that off (Detect as Bridge?) or you could just change the bridge settings to your normal print settings.