#!/usr/bin/perl -w

use strict;
use Benchmark;
use File::Find;

my @paths = (split/\:/,$ENV{PATH});

sub which1 {
        my $filename= "test.txt";
        foreach my $pathname (@paths) {
                print "$pathname/$filename\n" if ( -e "$pathname/$filename" );
        };
}

sub which2 {
        my $filename = "test.txt";
        finddepth sub {print "$_\n" if ( /$filename$/)} , @paths;
}

timethese (100, {'whichone' => \&which1, 'whichtwo' => \&which2});