On the speed question, I actually find Perl considerably faster than sed in a lot of use-cases, if there's enough processing to dominate the slightly higher startup costs of Perl.

For example, at one point I had reason to take a gigantic single-line textfile, and break it into lines based on a specific 3-letter pattern that didn't occur anywhere else:

   s/ABC/A\nC/g

In whatever sed comes with Debian, this took about 10 minutes, CPU-bound, for a 2-gigabyte file. With Perl: 1.5 minutes, IO-bound. Not too sure why. Maybe sed runs everything through the regex engine, while Perl special-cases constant strings? Perhaps Perl has better buffer management for processing gigabytes of text? I haven't done any real testing.