But I believe this needs to be done in sed than in perl. [...] I did some time comparison for both perl and sed and it turns out that sed has better performance

$time sed -i 's/sri/harry/' *
sed -i 's/sri/harry/' *  0.00s user 0.01s system 37% cpu 0.016 total

$time perl -pi -e 's/harry/sri/' 
perl -pi -e 's/harry/sri/' *  0.01s user 0.01s system 62% cpu 0.029 to
+tal
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So, you suggest to optimize a one-shot command run every few day, weeks, or months for a total execution speed advantage of 10 milliseconds on your machine, based on one single run of each command? Are you serious?

(If yes, let me suggest to use a one-letter shell alias for "perl -pi -e". This saves you 10 keystrokes and thus gains you much more than 10 milliseconds, even if you can type really fast.)

Alexander