I have been running for about 20 years, mostly 10-21 km over the past few years. This past year I've transitioned into running in Vibrams - in the simplest model I found - and about two month ago I stopped running in "regular" shoes altogether.
typically jog for the first few km, and then speed up for the last 5.5 km of my run, which is done on a flat, paved bike path/pedestrian walkway. I have more than a hundred times for this particular section, and since I started running it in the Vibrams, my average time has dropped dramatically. I'd say that for the past year, I've been doing it in 26-30 minutes, and in the past month from 25-27. Furthermore, in the past my times were all over the place- on a bad day I'd end up jogging it (hence 30 minutes) and on a good day it could be 26. In the Vibrams it feels like I can't really slack off and jog slowly, even on days I feel lackluster.
Does this make sense? Do minimalist running shoes force you into better form and improve your times?