Anonymous subs are cheaper in terms of usage (invoking a named sub includes a round-trip to the symbol table) and memory.

Named subs:

use strict; use warnings;
my $begin;
BEGIN { chop( $begin = `ps -o vsz= $$` )}

eval "sub F_$_ {
    my( \$a, \$b, \$c ) = \@_; 
    my \$x = $_; 
    return \$a * \$b - (\$x + \$c); 
}" for 1..1e4;

END {
    chop( my $end = `ps -o vsz= $$` );
    print "$end - $begin = ",$end - $begin, "\n";
}
__END__
60924 -  22228 = 38696

[download]

Anonymous subs:

use strict; use warnings;
my $begin;
BEGIN { chop( $begin = `ps -o vsz= $$` )}
my @ary;
$ary[$_] = eval "sub {
    my( \$a, \$b, \$c ) = \@_; 
    my \$x = $_; 
    return \$a * \$b - (\$x + \$c); 
}" for 1..1e4;

END {
    chop( my $end = `ps -o vsz= $$` );
    print "$end - $begin = ",$end - $begin, "\n";
}
__END__
53356 -  22228 = 31128

[download]

That makes ca. 3.1kB per anonsub, 3.9 per named sub. Slightly different numbers than BrowserUk's above, but also slightly different architecture and version of perl:

perl 5, version 14, subversion 2 (v5.14.2) built for x86_64-linux-gnu-thread-multi

update: The ca. 750 extra bytes for named subs may well be just the cost of allocating a GLOB for the subroutine in the symbol table, which comes wiith SCALAR, HASH, ARRAY, CODE and FILEHANDLE slots. Currently I don't recall whether they are autovivified as needed or allocated in one go.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re: Memory efficiency, anonymous vs named's vs local subroutines by shmem
in thread Memory efficiency, anonymous vs named's vs local subroutines by thanos1983

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