Curious. It shouldn't be doing any more searching than grep would, assuming you are reading in one line at a time. (if you slurped the file in as one long line that could slow you down a lot). How did you adapt the above code for your situation? Perhaps if you posted the code we might have a better idea of why your program is so slow.

When I created a dummy file with the data above repeated 10,000 times (equivalent to a 6.6M file) parsing took only 0.71 seconds (wall clock time). When I upped the size by repeating the file 1,000,000 times (equivalent to a 660M file, more than half a gigabyte) it took 26 seconds.

Best, beth