[0] Perl> sub a(){ 1 }; sub b(){ return 1; };; [0] Perl> cmpthese -1,{ a=>q[ a() for 1 .. 1000;], b=>q[b() for 1 .. 1 +000;] };; Rate b a b 4668/s -- -80% a 23195/s 397% --
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$ perl -E 'use Benchmark qw(timethese cmpthese); sub a() { 1 }; sub b() { return 1 }; cmpthese -1,{ a=>q[ a() for 1 .. 1000;], b=>q[b() for 1 .. 1000;] };'
     Rate    b    a
b  2694/s   -- -88%
a 23209/s 761%   --
$ perl -E 'use Benchmark qw(timethese cmpthese); sub a { 1 }; sub b { return 1 }; cmpthese -1,{ a=>q[ a() for 1 .. 1000;], b=>q[b() for 1 .. 1000;] };'
    Rate   b   a
b 2595/s  -- -8%
a 2823/s  9%  --