make_immutable should make accessors faster through 'inlining'.
Not as I understand it. I believe accessors are always inlined. Rather, make_immutable speeds up object creation. Using your test framework with the following tests 
my %tests = (
    Moose     => sub { $x= MyClass    ->new },
    MooseImmu => sub { $x= MyImmuClass->new },
);

[download]

Yields: 

              Rate     Moose MooseImmu
Moose      15360/s        --      -94%
MooseImmu 261482/s     1602%        --

[download]

Update:

I've been grepping pods...

Moose::Manual::BestPractices:

The "make_immutable" call allows Moose to speed up a lot of things, most notably object construction.

Moose::Meta::Class:

$metaclass->make_immutable(%options)
...
Also, since Moose always inlines attributes...

In reply to Re: Moose immutable speedup? by FunkyMonk
in thread Moose immutable speedup? by jethro

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