One important tip, is that if the text you are searching for (and therefore the regular expression) is not know at perl compile time, then you can explicitly compile the regular expression at runtime, which will improve performace.
qr gains in performance if it helps compiling the same pattern multiple times. It has nothing at all to do whether a pattern is known at perl compile time or not.

In reply to Re^2: Alternation vs. looping for multiple searches. by JavaFan
in thread Alternation vs. looping for multiple searches. by kprice++

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