Hello DARK_SCIENTIST and welcome to the monastery.

Give Hash::Ordered a try. There is also MCE::Shared::Ordhash which can be constructed as a non-shared object. The two implementations are reasonably fast. The OO interface is faster whenever performance is desired.

use Hash::Ordered;
use MCE::Shared::Ordhash;

tie my %h1, 'Hash::Ordered', @pairs;
tie my %h2, 'MCE::Shared::Ordhash', @pairs;

my $h3 = Hash::Ordered->new( @pairs );
my $h4 = MCE::Shared::Ordhash->new( @pairs );
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MCE::Shared::Ordhash supports OO and hash-like dereferencing at the same time. It's quite nice having OO for maximum performance and dereferencing when needed.

my $oh = MCE::Shared::Ordhash->new();

$oh->set( hello => "there" );
$oh->{hello} = "there";  # on-demand hash-like dereferencing
$oh->assign( @pairs );
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Examples.

use Hash::Ordered;

tie my %h1, 'Hash::Ordered', qw( title1 foo title2 bar title3 baz );
my @labels1 = keys %h1;

my $h2  = Hash::Ordered->new(qw( title1 foo title2 bar title3 baz ));
my @labels2 = $h2->keys;
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Both Hash::Ordered and MCE::Shared::Ordhash are light on memory consumption.

Regards, Mario.