Just a heads up: Our site has over 600,000 users in Wordpress. When creating a new form in GF, the form_detail.php makes use of the wp_dropdown_users() function to populate the 'Default Post Author' field. As a result, it attempts to load all 600+k users into the field.
This causes a massive load time and occasionally the page just craps out and won't load at all. When I commented out the use of wp_dropdown_users() in form_detail.php, everything loaded fine.
This temporary solution will hold us over, but it'd be great if you could take this issue into consideration in future releases.