Definitely, 1GB file is quite huge! Do you really think that it is possible to improve the performance in this case? Any way there are two another hints given by other monks: 1) use index or 2) combine few small regexps into the bigger one. Also you can remove the part creating the regexps out of the loop: create regexps before looping and use "compiled" regexps within the loop.

In reply to Re^3: Multiple patterns match in a big file and track the counts of each pattern matched by siberia-man
in thread Multiple patterns match in a big file and track the counts of each pattern matched by ansh007

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