Yep, the K interpreter is pretty mediocre (it is very small and the language is inherently pretty fast, but the interpreter is otherwise not very advanced¹) but being directly integrated with a very optimized in-memory column-store database means it smokes anything else. Even the massive engineering effort in a JVM+RDBMS simply can't compete with running K directly on memory-mapped files.

1. I believe they added SIMD support a year or two ago and got a massive (2-10× IIRC) speedup.