I tried
elm-test
Duration: 665 ms
Passed: 880
Failed: 0
real 0m5.436s
user 0m12.894s
sys 0m7.801s
lydell/node-test-runner#js
Duration: 636 ms
Passed: 880
Failed: 0
real 0m1.496s
user 0m4.137s
sys 0m0.758s
Your fork was consistently faster. 6 secs vs 2 secs.