slice and print the Twisted Bottle: [www.thingiverse.com]
at 0.2mm layer height it's fairly obvious at 0.1mm it's disastrous.

when it gets to the bottle part, and it's not printing the lid as well any more, it stops, retracts, goes up a z level, extrudes and continues.
at 0.2mm I get a little blob at this point at 0.1mm I get a large blob and had to stop the print it got so bad.
the wait time at this point also caused problems with temperature of the part at this point, even though I had a fan on it.

retraction settings:
Length 1
Lift 0
Speed 30
Extra Length 0
Minimum travel after retractions 2

My guess is it's just ignoring the minimum travel when doing a z move.

Possible feature request:
what if when doing such parts (perimeter only) it didn't even stop to do a Zmove, but gradually Zmoved while printing.
ie print in three dimensions rather than two dimensions, stopping, then going up.
think of the tool moving like a spring or a slinky.

think I may have fixed the blobbing, seems that the default acceleration settings were way too high. will print this object again and see how it comes out.