Rate primes_all         ch         jg    ch_opt2
primes_all 1.75/s         --       -96%       -97%       -97%
ch         49.8/s      2751%         --        -4%       -11%
jg         51.9/s      2869%         4%         --        -8%
ch_opt2    56.2/s      3117%        13%         8%         --


##</code><code>##

#! /usr/bin/perl
use warnings;
use strict;

####
print '
use strict;
use warnings;

use Benchmark qw{ cmpthese };

sub primes_original {
    my $n = shift;
    return if $n < 2;

    my @primes = (2);
    for my $i (3 .. $n) {
        my $sqrt = sqrt $i;
        my $notprime;
        for my $p (@primes) {
            last if $p > $sqrt;

            $notprime = 1, last if 0 == $i % $p;
        }
        push @primes, $i unless $notprime;
    }
    return @primes
}
';

my @givenp = qw(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149);

foreach my $num (0..$#givenp){
####
print '

sub primes_opt_till_'.$givenp[$num].' {
    my $n = shift;
    return if $n < 2;

    my @primes = (2);
    for my $i (3 .. $n) {
';
foreach my $quot ( 0 .. $num ){
####
print "\t\t\t\t".'if($i%'.$givenp[$quot].'==0){next}'."\n";
}
####
print '
        my $sqrt = sqrt $i;
        my $notprime;
        for my $p (@primes) {
            last if $p > $sqrt;

            $notprime = 1, last if 0 == $i % $p;
        }
        push @primes, $i unless $notprime;
    }
    return @primes
}
##

';
}

####
print '
cmpthese(-10,
        {
primes_original => \'primes_original (10000)\',
';
foreach my $num (0..$#givenp){
    print "opt_till_$givenp[$num] => 'primes_opt_till_$givenp[$num] (10000)',\n";
}
####
print'
        });
';

##</code><code>##

sub primes_opt_till_79 {
    my $n = shift;
    return if $n < 2;

    my @primes = (2);
    for my $i (3 .. $n) {
				if($i%2==0){next}
				if($i%3==0){next}
				if($i%5==0){next}
				if($i%7==0){next}
				if($i%11==0){next}
				if($i%13==0){next}
				if($i%17==0){next}
				if($i%19==0){next}
				if($i%23==0){next}
				if($i%29==0){next}
				if($i%31==0){next}
				if($i%37==0){next}
				if($i%41==0){next}
				if($i%43==0){next}
				if($i%47==0){next}
				if($i%53==0){next}
				if($i%59==0){next}
				if($i%61==0){next}
				if($i%67==0){next}
				if($i%71==0){next}
				if($i%73==0){next}
				if($i%79==0){next}

        my $sqrt = sqrt $i;
        my $notprime;
        for my $p (@primes) {
            last if $p > $sqrt;

            $notprime = 1, last if 0 == $i % $p;
        }
        push @primes, $i unless $notprime;
    }
    return @primes
}


##</code><code>##

                  Rate
primes_original 74.2/s
opt_till_2      91.8/s
opt_till_3       108/s
opt_till_5       119/s
opt_till_7       128/s
opt_till_11      134/s
opt_till_13      140/s
opt_till_17      142/s
opt_till_19      151/s
opt_till_23      156/s
opt_till_29      158/s
opt_till_31      164/s
opt_till_37      165/s
opt_till_149     169/s
opt_till_139     169/s
opt_till_41      172/s
opt_till_131     174/s
opt_till_137     174/s
opt_till_127     175/s
opt_till_47      176/s
opt_till_113     178/s
opt_till_43      180/s
opt_till_109     181/s
opt_till_53      181/s
opt_till_107     184/s
opt_till_59      184/s
opt_till_103     186/s
opt_till_101     188/s
opt_till_61      188/s
opt_till_97      189/s
opt_till_67      190/s
opt_till_71      190/s
opt_till_73      191/s
opt_till_89      191/s
opt_till_83      192/s
opt_till_79      193/s