As mentioned in other discussions 'Add' functionality on forms for fields with unlimited cardinality is overly slow, making it practically unusable, when user has to wait (sometimes tens of) seconds for new field to appear on screen after Add button pressed. This is a performance issue related to the field and form functionality, and it's critical due to ubiquitous nature of entities and their fields.
Link to one of the discussions on this topic.

Comments

Version: 7.26 » 7.x-dev

Core issues are now filed against the dev versions where changes will be made. Document the specific release you are using in your issue comment. More information about choosing a version.