Interesting. But they are quite wrong (see above).

Actually, you're quite wrong. And if you learnt to use strict you'd have seen your mistake.

Here are the results of your benchmark once your mistake is corrected.

[18:46:32.42] P:\test>junk
              Rate Ref_Named     Named  Ref_Copy     Shift       POE  
+  Normal
Ref_Named 119185/s        --       -3%      -35%      -81%      -83%  
+    -84%
Named     122333/s        3%        --      -34%      -81%      -83%  
+    -84%
Ref_Copy  183991/s       54%       50%        --      -71%      -74%  
+    -76%
Shift     639848/s      437%      423%      248%        --       -9%  
+    -17%
POE       701269/s      488%      473%      281%       10%        --  
+     -9%
Normal    768699/s      545%      528%      318%       20%       10%  
+      --
[download]

And that should absolutely zero surprise to anyone: OBJECT, KERNEL, HEAP, and SESSION are all subs which would mean subroutine calls.

You're the one in for the surprise. They aren't subroutine calls, they are constant subroutine calls. What difference does that make?

It means that at compile time, Perl can detect that they are constant subroutines.

[18:43:58.10] P:\test>perl -MO=Deparse -e"use constant{ONE=>1,TWO=>2};
+ for( ONE .. TWO) { print }"
use constant ({'ONE', 1, 'TWO', 2});
foreach $_ (1 .. 2) {
    print $_;
}
-e syntax OK
[download]

Did you spot your error yet? use strict would have told you way back up ^ there somewhere--but I guess that is another "artificial box" you'd rather stay out of.

So, what do you think we should put a pox on now? Flying by the seat of your pants! :)