Several issues were noticed when working with dynamically loaded layers including deadlocks, race conditions and access violations. The dynamic (i.e. extent-based) loading and rendering of large featuresets has been drastically reworked and aligned with how regular feature sets are rendered.
For advanced applications an additional method for OGR layers was added called ExtendFromQuery. This method allows the developer to extend the currently loaded feature set using an OGR SQL query. Features matching the query are added (or updated if a feature with the same OGR_FID already exists) to the feature set.
In previous iterations the ReloadOgrLayerFromSource (on the Map_Layer) was already adapted to allow reloading an entire dynamically loaded feature set.