Precompile your patters. Example:

my $re = qr/this RegEx will be used 10,000 times/;
open FH, "<file.dat" or die "Error : $!\n";
while (<FH>){
   process() if /$re/;
}
close FH;
[download]

You can refer to perldoc perlretut for additional information.

--perlplexer