Clojure's rest arguments are quite fast, as it turns out:

gistfile1.txt

user=> (doseq [f [(fn [& r] r) list vector]] (time (dotimes [_ 10000000] (f 1 2))))
"Elapsed time: 89.534 msecs"
"Elapsed time: 1619.788 msecs"
"Elapsed time: 659.573 msecs"
nil
user=> (doseq [f [(fn [& r] r) list vector]] (time (dotimes [_ 100000000] (f 1 2))))
"Elapsed time: 284.97 msecs"
"Elapsed time: 16061.555 msecs"
"Elapsed time: 6207.421 msecs"
nil
user=>