You may have missed is that it's caching a blessed scalar ref, which means that on the next new call, it can just pop an item of the cache instead of blessing a new object.

Blessing a ref takes an infinitesimal amount of time. My benchmark: 

package STR;
use Class::Std::Fast; ## cache => 1;

package main;
use Time::HiRes qw[ time ];

my $start = time;
STR->new for 1 .. 1e6;
printf "Took %.8f seconds\n", ( time - $start ) / 1e6;

__END__
## With caching
c:\test>junk64
Took 0.00002447 seconds

## Without caching
c:\test>junk64
Took 0.00002391 seconds

[download]

And if you removed all the cache related conditionals, it would be quicker still.

It would also avoid your original problem

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
RIP an inspiration; A true Folk's Guy

In reply to Re^4: Class::Std::Fast cache and threads by BrowserUk
in thread Class::Std::Fast cache and threads by Boldra

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