duh! ok, so I changed the code to the following (by the way, am I the only one interested in playing around with Inline)? :

#! /usr/bin/perl -w

use strict;
use Benchmark;

my @a = (1..500000);

use Inline C => <<'ADDUP_END';
double addup( SV* stub, ... ) {
    double total = 0;
    int i;
    Inline_Stack_Vars;
    for( i = 0; i < Inline_Stack_Items; ++i ) {
        total += SvNV(Inline_Stack_Item(i));
    }
    return total;
}
ADDUP_END

timethese shift || 100, {
        '$_' => sub {
                my $count = 0;
                foreach( @a ) {
                        $count += $_;
                }
        },
        'my' => sub {
                my $count = 0;
                foreach my $var( @a ) {
                        $count += $var;
                }
        },
        'Inline' => sub {
                my $count = addup( @a );
        },
};
[download]

now I see around a 7% gain in favour of lexicals (i.e., barely above the noise level). It's not the 25% I was expecting. Heh, the Inline method is close to an order of magnitude faster!

update: tip o' the hat to Hofmator for spotting an orphan $rec.

update 2001-08-06: in my travels through the older nodes in the monastery, I encountered another thread that deals with a similar topic: is 'my' that much faster than 'local'?. It may be of interest.

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g r i n d e r