Yes, there are, but I mostly know of ones in print. The O'Reilly Perl 5 book has a two good sections on efficiency and coding style on pages 537-550. The O'Reilly Regular expression book has a lot of information scattered in it about what makes particular regular expressions fast or slow. (In particular, do not use $`, $&, or $'.)

Naturally, the entire Perl Cookbook is a resource on how to do particular tasks efficiently, and makes a good starting point. Lastly, there is this great site about perl where you can search for all things perl related. If you had a particular question, I'm sure you could find the answer there. :)

-Ted