#!/usr/bin/perl -w
# usage : ./this_script.pl < input_file > captured_benchmarks
use strict;
use Benchmark;
my @data=<>;
my (@res1,@res2,@res3);
timethese (100000000,
	{ grep_and => q{
	@res1 = grep /GGGGGACACCTTCTCTCTCT/ && /RH_MEa0001bG06/, @data;
	},
	double_grep => q{
	@res2 = grep /GGGGGACACCTTCTCTCTCT/,grep /RH_MEa0001bG06/,@data;
	},
	lookahead_grep => q{
	@res3 = grep /^(?=.*GGGGGACACCTTCTCTCTCT)(?=.*RH_MEa0001bG06)/,@data;
	}
}
);

##</code><code>##

Benchmark: timing 100000000 iterations of double_grep, grep_and, lookahead_grep...

double_grep	:
27 wallclock secs (26.98 usr +  0.00 sys = 26.98 CPU) @ 3705899.79/s (n=100000000)

grep_and	:
24 wallclock secs (23.05 usr +  0.00 sys = 23.05 CPU) @ 4338959.52/s (n=100000000)

lookahead_grep	:
24 wallclock secs (22.83 usr +  0.00 sys = 22.83 CPU) @ 4380585.25/s (n=100000000)