Moose has lazy attributes that do what you want (if I understood your question correctly), see Moose::Manual::Attributes (search for "lazy").

But if performance is a big concern to you, you should evaluate if Moose doesn't slow you down too much. Hand-coding lazy attributes isn't all that difficult. 

use 5.010; # for //=, but can be rewritten without it

sub lazy_foo {
   $_[0]->{lazy_foo} //= $_[0]->construct_foo;
}

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Perl 6 - second systems done right

In reply to Re: Object design/structure with sub-objects (Moose) by moritz
in thread Object design/structure with sub-objects (Moose) by Cagao

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