what do you mean by aliasing? if you mean accessing complex structures $x->{'a'}->{'b'}->[$loop_index] , I always put the static part of the data structure outside the loop and use that "alias?" inside the loop

perlglossary#alias
• alias

  A nickname for something, which behaves in all ways as though you’d used the original name instead of the nickname. Temporary aliases are implicitly created in the loop variable for foreach loops, in the $_ variable for map or grep operators, in $a and $b during sort’s comparison function, and in each element of @_ for the actual arguments of a subroutine call. Permanent aliases are explicitly created in packages by importing symbols or by assignment to typeglobs. Lexically scoped aliases for package variables are explicitly created by the our declaration.

just search and you'll find many discussions in the archive regarding the complicated mechanisms involved here, including the divide between package and private vars, closure inside the loop, etc ...

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

got it, thanks.

use Benchmark 'cmpthese';

cmpthese(-2, {
    predecl => '
        my $y;
        my $x;
        for $x (1..10000) { $y+=$x }
    ',
    lexical => '
        my $y;
        for my $x (1..10000) { $y+=$x }
    ',
    aliased => '
        my $y;
        for (1..10000) { $y+=$_ }
    ',
});
[download]

Seems you are right!

          Rate aliased lexical predecl
aliased 3733/s      --     -3%     -5%
lexical 3858/s      3%      --     -2%
predecl 3938/s      5%      2%      --
[download]