I could probably have countered it, too, in the same language during the challenge back when I used it. I found the incremental, per-function compilation feature reduced compilation time of most changes to a fraction of a second. Most of time in programming is spent thinking, tweaking, debugging, dealing with 3rd-party libs, etc. I don't think a difference in the source-to-execution part of under 1 second is going to make a big deal.

It's high-speed iteration of code one is exploring that makes both REPL's and incremental compilation superior for productivity to full compilation.