This might be a situation where study might be helpful. Here's section from the docs: 

Takes extra time to study SCALAR ($_  if unspecified) in anticipation 
+of doing many pattern matches on the string before it is next modifie
+d. This may or may not save time, depending on the nature and number 
+of patterns you are searching on, and on the distribution of characte
+r frequencies in the string to be searched--you probably want to comp
+are run times with and without it to see which runs faster. Those loo
+ps that scan for many short constant strings (including the constant 
+parts of more complex patterns) will benefit most.

[download]

-xdg

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In reply to Re: Optimizing many many regex matches by xdg
in thread Optimizing many many regex matches by BUU

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