wp-e-commerce/WP-e-Commerce — pull request #1406 by JeffPyeBrook (2014-06-17 16:00:33+00:00)
Title: Don't save cart to database when nothing has changed

Calculate a cart signature when a cart is loaded from the database
Recalculate the signature when a cart is being saved, compare the signatures, don't save if they are not different.