C:\test>226666 Benchmark: running substr_it, unpack_it , each for at least 3 CPU seconds ... substr_it: 4 wallclock secs ( 3.17 usr + 0.00 sys = 3.17 CPU) @ 2375.99/s (n=7520) unpack_it: 4 wallclock secs ( 3.38 usr + 0.00 sys = 3.38 CPU) @ 4371.56/s (n=14754) Rate substr_it unpack_it substr_it 2376/s -- -46% unpack_it 4372/s 84% -- Results tally C:\test> #### #! perl -slw use strict; use vars qw[$line @s @s2 @u1 @u2]; use Benchmark qw[cmpthese]; $line = (join'','a' .. 'y') x 40; sub substr_it{ my @bits; $bits[0] = substr $_[0], 413, 30; $bits[1] = substr $_[0], 373, 30; $bits[2] = substr $_[0], 343, 30; $bits[3] = substr $_[0], 245, 15; $bits[4] = substr $_[0], 679, 30; $bits[5] = substr $_[0], 10, 10; $bits[6] = substr $_[0], 900, 100; $bits[7] = substr $_[0], 500, 2; $bits[8] = substr $_[0], 313, 30; $bits[9] = substr $_[0], 844, 44; $bits[10] = substr $_[0], 111, 1; $bits[11] = substr $_[0], 100, 100; $bits[12] = substr $_[0], 454, 30; $bits[13] = substr $_[0], 240, 3; $bits[14] = substr $_[0], 236, 4; @bits; } sub unpack_it{ my $fmt = '@413A30 @373A30 @343A30 @245A15 @679A30 @10A10 @900A100' . '@500A2 @313A30 @844A44 @111A1 @100A100 @454A30 @240A3 @236A4'; unpack( $fmt, $_[0]); } cmpthese( -3, { substr_it => '@s = substr_it $line;', unpack_it => '@u1 = unpack_it $line;', }); print 'Results tally'; __END__