Q/KDB is 600kb, also runs code on all three major operating systems (and a few minor ones). It's also about 1000x faster than Java/Spark[1].

1000x slower doesn't sound like a huge win to me; it sounds like a huge cost, so my question is what do we gain by making our programs 1000x slower?

[1]: http://tech.marksblogg.com/benchmarks.html