This has nothing to do with your speed issue, but I thought I'd offer a less cluttered version of your sub gen_reportfile_name:

sub gen_reportfile_name {
    my ($mday, $mon, $year) = (localtime)[3,4,5];
    $reportfile = sprintf '/dirhere/%4d%02d%02dtalkpath', $year+1900, 
+$mon+1, $mday;
}
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This uses an array slice to extract only the elements of interest from the list returned by localtime.