That depends on a whole lot of factors. In old perls, that was true; modern perls have optimisations to avoid recompiling patterns if the interpolated variables haven’t changed.

However, note that a match such as $foo =~ /$bar/ is magical if $bar is a pattern precompiled with qr, in that the pattern compilation phase is skipped completely. (This applies when the pattern consists of nothing but the interpolated variable.)

And finally, the (?{}) delayed evaluation construct lets you embed pre-compiled patterns in another pattern without recompiling the embedded pattern.

Makeshifts last the longest.

In reply to Re^3: speeding up a regex by Aristotle
in thread speeding up a regex by Anonymous Monk

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