performancepaper VS ultrarand

There is a review of the study at https://github.com/joinr/performancepaper. Basically by using optimization tricks (recur for recursive function call, unchecked math, using Java types, etc.) Tom meets/beats the performance of Java.

I did a contrast with someone's graduate thesis that aimed to analyze clojure vs. java performance and made some weak claims. The rep is here, and it's really the org file. Sort of a worked example of optimizing code.

I often see people knocking on Clojure saying its performance is bad when they are still not familiar with all the core library has to offer and what idiomatic performant Clojure can look like. Take a look here for some examples by joinr

There's a pretty interesting discussion on primitive arrays where the user is trying to match java performance exactly with an array-based thing that's simple enough to port, but is still a hair off due to clojure's default toward longs even for indexing (java wants int for array indices, so casts are necessary). Ended up getting identical performance using JiSE here, although the clojure variant with uncheckedIntCasts was fairly close (just not "equivalent to Java" per the common trope).

There's an intersting thread on zulip regarding getting identical performance with java arrays. Normally if you're using unchecked math and working with primitives, then you should get with a hair of java (not 2-3x slower). The remaining differences are due to uncheckedIntCast since Clojure forces longs for indices and java wants ints. The difference is I'm in the realm of nanos but is there. You can eliminate it with custom bytecode like with the JISE library which is fairly painless. Example .