You might want to start with Simple Module Tutorial, authored by the great tachyon. You may also find merlyn's book, published by O'Reilly, called "Perl Objects, References and Modules" helpful, as I did.

As for efficiency, that has a lot to do with what you're trying to accomplish, and what algorithms you use to accomplish the task at hand. We can't be very helpful in that respect without knowing what kind of a module you have in mind.

I'd suggest as a starting point the perlmod documentation. Once you've read that, look at the other documentation that it links to. After that, you might try the book 'Learning Perl Objects, References & Modules', or if it's specifically an OO module, 'Object Oriented Perl'.

For the efficiency side of things, I find that's a much harder thing to teach. (I look at it, to a certain degree, to be more of an art than a science), and tuning is a never ending process that involves too many variables (input characteristcs, memory, cpu power, disk i/o, etc.) to be solved absolutely. Perhaps someone else can give advice on this topic.

And anyother reference books to create a module effectively

There's also "Writing Perl Modules for CPAN" that's now available for download.