Benchmark: running File::Copy::cp($a, $b), system('cp', $a, $b) for at least 3 CPU seconds...
File::Copy::cp($a, $b):  4 wallclock secs ( 0.17 usr +  3.18 sys =  3.35 CPU) @ 339.70/s (n=1138)
system('cp', $a, $b): 29 wallclock secs ( 0.13 usr  3.21 sys +  1.43 cusr 24.26 csys = 29.03 CPU) @ 965.27/s (n=3224)