When adding or removing elements from a non-database-ordered (no order by or order column - which require strict order to be maintained) lazy proxied collection which is a relationship to other entities, OpenJPA loads the collection before performing the operation. This can be very expensive if an operation is only adding or removing items from the collection. I created a feature that, when switched on, allows non-indexed add and remove operations to be performed on a collection without triggering a load. The collection will get loaded (and reconciled, if necessary) when an operation is performed that requires a load, such as iteration, size, isEmpty, etc. Currently, the feature can be enabled for the using this new attribute on the ProxyManager.
<property name="openjpa.ProxyManager" value="delayCollectionLoading=true"/>
The basics have been added to field mappings/metadata such that this could be enabled on a per-field basis in the future.