First guess, thankfully shot down by chromatic: The o modifier tells Perl to only compile the regex once, so I believe the two seconds you saved were Perl not compiling the same regex ten million times. Recompiling a constant didn't make sense to me so I am glad I was wrong here.

Second: Retesting, it seems that it's /g that speeds things up, not /o. Perhaps someone more familiar with Perl internals can shed some light.

Finally: Ikegami has it.

In reply to Re: Why this code run faster? by gamache
in thread Why this code run faster? by Gangabass

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