To me it was obvious that the time-to-compile measurement for ClojureScript was all wrong. It's a common, but annoying mistake people who aren't used to the JVM make. Startup Time != Compile Time.
If it started once and watched files for changes, it would only be the compile time (which, if fast, would be great). As it is, the total time is the only one that counts, as it is the one that affects your productivity.
JRuby guys were so aware of this that they actively promoted nailgun[1].
