Calling multi arity fns seems to degrade performance.

[thomasmulvaney]

Here is a basic example:

(ns bad.performance.test
  (:require [pixie.time :as time]))

(println "No issue")
(dotimes [i 10]
  (t/time (reduce (fn ([_ _] nil)) nil (range 10000000))))

(println "Multi-arity issue")
(dotimes [i 10]
  (t/time (reduce (fn ([_ _] nil) ([_])) nil (range 10000000))))  

The output is below:

"Elapsed time: 36.200522 ms"
"Elapsed time: 28.493774 ms"
"Elapsed time: 32.007228 ms"
"Elapsed time: 32.310871 ms"
"Elapsed time: 31.159702 ms"
"Elapsed time: 30.122666 ms"
"Elapsed time: 27.858281 ms"
"Elapsed time: 27.836514 ms"
"Elapsed time: 29.166467 ms"
"Elapsed time: 29.809780 ms"
Multi-arity issue
"Elapsed time: 255.087997 ms"
"Elapsed time: 294.007728 ms"
"Elapsed time: 336.469480 ms"
"Elapsed time: 369.489639 ms"
"Elapsed time: 433.686057 ms"
"Elapsed time: 539.577651 ms"
"Elapsed time: 654.685995 ms"
"Elapsed time: 776.953019 ms"
"Elapsed time: 1090.215928 ms"
"Elapsed time: 835.943882 ms"

The performance seems to constantly degrade when a multi-arity fn is used.