It seems like `--gc:arc` or `--gc:orc` are a bit slower than without any `--gc` argument. No extra `--gc`: 2.88 seconds `--gc:markAndSweep`: 1.77 seconds `--gc:arc`: 5.46 seconds `--gc:orc`: 6.01 seconds
(The second/faster example without closure doesn't change much with any of these options)
