Use 

while(<$fh_big_file>) {
  print if (/$regex/o .. /^END_OF_BLOCK/);
}

[download]

to avoid recompilation of the regex.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re: Performance of assambled regex by shmem
in thread Performance of assambled regex by Foodeywo

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