Anyway, I have added code to benchmark the sorting algorithms provided by Sort::Key and Sort::Key::Radix...

...

use Sort::Key::Radix;
my $skr = sub
    {
        my @sortedKeys = Sort::Key::Radix::nkeysort { $hash{$_}{Size} 
+} keys %hash
    };

use Sort::Key;
my $sk = sub
    {
        my @sortedKeys = Sort::Key::nkeysort { $hash{$_}{Size} } keys 
+%hash
    };



cmpthese(
   -5,
   {
       ClassicGRT => $rcClassicGRT,
       ClassicST  => $rcClassicST,
       Jethro     => $rcJethro,
       Simple     => $rcSimple,
       SK         => $sk,
       SKR        => $skr
   } );
[download]

             Rate    Simple ClassicST ClassicGRT    Jethro         SK 
+       SKR
Simple     3.08/s        --      -45%       -69%      -70%       -78% 
+      -80%
ClassicST  5.64/s       83%        --       -42%      -45%       -60% 
+      -63%
ClassicGRT 9.79/s      218%       74%         --       -5%       -31% 
+      -36%
Jethro     10.3/s      234%       83%         5%        --       -27% 
+      -32%
SK         14.1/s      359%      151%        44%       37%         -- 
+       -7%
SKR        15.2/s      394%      170%        55%       48%         8% 
+        --
[download]