Normally when I use a class as a selector I try to use an \"id\" selector with it so it does not search through the entire page but only an area where the class would be.
You can combine multiple selectors with a comma:
$('#Create .myClass,#Edit .myClass').plugin({options here});
Or if you're going to have a bunch of them, you could add a class to all your form elements and then search within that class. This doesn't get you the supposed speed savings of restricting the search, but I honestly wouldn't worry too much about that if I were you. Browsers do a lot of fancy things to optimize common operations behind your back -- the simple class selector might be faster.