Yeah, actually, I just went back in git trying to find the commit that sped things up and found that it always took roughly 12.5 seconds with current firmware master binary (79900 bytes). It did get a tiny bit faster at some point (12.55 seconds down to 12.47 seconds). I’m not confusing it with with avrdude, but I might’ve heard it from someone else on the Spark team and not verified. The speed up might’ve been somewhere else in our factory programming process rather than dfu-util itself.
Ah, OK, I found an email conversation between me and @Dave on April 23rd where he suggested the latest dfu-util made our total factory test and programming time a handful of seconds faster, which was probably an accumulation of many small differences.
In any case, there are several improvements in 0.8 (released Sept 13, 2014) since 0.7 was released Oct 7, 2012. Many of the improvements are specific to the Spark Core and came directly out of discussions here in the community!
In particular, I know this one was a big deal: