Glad you noticed the improvements in diff. We are continually working to improve the performance, memory usage and actual results. We have very little control over memory consumption but are working to reduce the usage in every way we can.
We will continue to work to improve this and if you have any specific requirements/wants please log a request on Feature Requests at the SQL Developer Exchange. This not only makes sure we don't forget, but also gives other users a chance to add their vote for the feature and provides a forum for you (the user base) to brainstorm on how you prefer it to work.
Edited by: Joyce Scapicchio on Nov 14, 2012 7:12 AM