Bench testing Clojure list comprehensions against map

bench-list.comprehension.clj

user> (use 'criterium.core)
nil
user> (def sites (vec (for [i (range 1000)] {:stations (vec (for [j (range 10)] [{:id (str i "-" j)}]))})))
#'user/sites
user> (bench (doall (mapcat (fn [site] (map :id (:stations site))) sites)))
Evaluation count : 74280 in 60 samples of 1238 calls.
             Execution time mean : 802.413222 µs
    Execution time std-deviation : 10.087328 µs
   Execution time lower quantile : 786.940250 µs ( 2.5%)
   Execution time upper quantile : 823.245990 µs (97.5%)
                   Overhead used : 1.685205 ns
nil
user> (bench (doall (for [site sites station (:stations site)] (:id station))))
Evaluation count : 72180 in 60 samples of 1203 calls.
             Execution time mean : 829.657186 µs
    Execution time std-deviation : 14.503025 µs
   Execution time lower quantile : 807.092634 µs ( 2.5%)
   Execution time upper quantile : 860.980596 µs (97.5%)
                   Overhead used : 1.685205 ns

Found 2 outliers in 60 samples (3.3333 %)
	low-severe	 2 (3.3333 %)
 Variance from outliers : 6.2879 % Variance is slightly inflated by outliers
nil
user> (bench (doall (mapcat (fn [site] (map :id (:stations site))) sites)))
Evaluation count : 75480 in 60 samples of 1258 calls.
             Execution time mean : 823.593130 µs
    Execution time std-deviation : 47.836024 µs
   Execution time lower quantile : 782.108014 µs ( 2.5%)
   Execution time upper quantile : 908.925568 µs (97.5%)
                   Overhead used : 1.685205 ns

Found 3 outliers in 60 samples (5.0000 %)
	low-severe	 2 (3.3333 %)
	low-mild	 1 (1.6667 %)
 Variance from outliers : 43.4368 % Variance is moderately inflated by outliers
nil
user> (bench (doall (for [site sites station (:stations site)] (:id station))))
Evaluation count : 76020 in 60 samples of 1267 calls.
             Execution time mean : 786.122713 µs
    Execution time std-deviation : 9.010751 µs
   Execution time lower quantile : 777.296567 µs ( 2.5%)
   Execution time upper quantile : 804.435049 µs (97.5%)
                   Overhead used : 1.685205 ns

Found 3 outliers in 60 samples (5.0000 %)
	low-severe	 2 (3.3333 %)
	low-mild	 1 (1.6667 %)
 Variance from outliers : 1.6389 % Variance is slightly inflated by outliers
nil