$ rustc listspawn.rs $ time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m58.843s user 3m39.459s sys 0m0.266s $ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 1m0.931s user 3m47.609s sys 0m0.291s $ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m57.967s user 3m36.343s sys 0m0.266s === MBP time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m18.593s user 2m17.990s sys 0m0.120s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m18.757s user 2m20.419s sys 0m0.116s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m18.505s user 2m18.653s sys 0m0.130s ==== MBA with -O (rustc 0.7) ==== bash-3.2$ rustc -O listspawn.rs warning: no debug symbols in executable (-arch x86_64) bash-3.2$ !t time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m10.573s user 0m36.498s sys 0m0.127s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m10.299s user 0m36.545s sys 0m0.119s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m10.330s user 0m36.555s sys 0m0.112s bash-3.2$ ==== MBP -O ==== time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.975s user 0m22.913s sys 0m0.022s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.922s user 0m22.950s sys 0m0.016s bash-3.2$ !! time ./listspawn [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.982s user 0m22.875s sys 0m0.019s ==== rust 0.8 time ./listspawn08 [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.964s user 0m23.187s sys 0m0.017s bash-3.2$ !! time ./listspawn08 [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.949s user 0m23.186s sys 0m0.019s bash-3.2$ !! time ./listspawn08 [565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580] [3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887, 3542887] real 0m2.980s user 0m23.193s sys 0m0.020s bash-3.2$