I think Truffle has a pretty good showing there that matches your description -- quick scripts don't get much help but longer-running ones have some pretty incredible improvements.
What's "quick" and "long running" in CPU secs on some machine?
What language implementation are we using as a baseline when we say "quick" and "long running"?
Otherwise someone might well say that 8 minutes with TruffleRuby is "long running" and CRuby 2.5 makes "some pretty incredible improvement" over that :-)
