RE: Virtual entity performance in Dynamics 365 Sales online?
Hi Kranis, thanks for reaching out.
No one is going to dispute the speed of the online system is not ideal. Hard to get the flexibility, configuration and customization abilities all in one system while remaining fast and responsive. Good news is it gets better with each version.
Virtual entities are difficult to implement. They require the source to have a GUID as a PK, which most sources do not have. They work best when anchored to another entity, not as the primary entity. Hard to reference child entities to a parent entity when the parent is virtual since data is not in the system.
Performance wise would depend on the source connection, and internet connection between source and D365 data center hosting your instance. In my opinion there is rarely a scenario where pulling data from another system would be faster than pulling data from within D365. The speed is not related to the database it is related to the UI which D365 provides, also customizations on the UI make this more difficult, plugins, etc also complicate the issue.
Hope this helps. Have a great day!