Here I want to clarify my question. CAN anyone help me to try to make the code work quickly?

I've tried a plethora of techniques, and it seems nothing works. I have 27 folders each with 12 files in them that I want to process (600-2500 KB, most ~1500 KB). Now, I've stripped the code down to just reading in the file and running a few lines of code (details at aforementioned node)
(I've read the file into @lines)

for my $curline(@lines) {
  next unless (reverse $curline) =~ /^\s*([05])/;
  $zeroat[$i++] = $ln_num if $1 == 0;
  $ln_num++;
}

for $i(@zeroat) {
  $lines[$i] =~ /^([0-9]+.?[0-9]*)\t.*([05])\s*$/;
  if ($1 > .5 && $2 == 0) {
    splice @lines,$i,1;
    @lines1 = @lines;
    @lines2 = splice @lines1,$i,$#lines1-$i+1;
  }
}
[download]

The code aside, though, it seems that just reading in these files takes too long. What can I do (do I need a faster computer, read line by line, optimize code, etc.)?