Very Weird Perl Running Time Difference

[Jeremy]

Hmmmmmm - now here's an odd one:

I'm running perl 5.8.3 from ActiveState (binary build 809) under WinXP SP2.

One little scriptette I've written chunters through about 11k lines in a text file, searches and removes certain lines and then appends the acceptable lines to a data file with some html coding, so the output file can be used as an html doc in another app.

Now here's the rub....

If I append the acceptable data to file.txt the script takes 1min 40 secs to run.

But if instead I append the data to file.html the script takes 50 mins 28 secs to run.

The file extension is the only difference, but I don't understand why it would have such a drastic impact on the script performance.

Any ideas?