Contacts app is very slow

I am using ownCloud version 9.1.4 and it works well so fare. Only the speed of the app Contacts is terribly slow. I have made a mysterious observation. The imported vCard file has 28 KB (the file is an export from my Google account). The oc_cards tables in the MySQL database are having 20 MB. For the most contacts I have included a picture, maybe this is the reason. Ist that possible? How can I speed this up? Data maintenance via browser is almost impossible.

Starting ownCloud 10 the backend offers more granular query options for vcards - this is basically a feature we did add to sabre dav some month back -

As soon as a giften javascript developer shows up we can use this feature on the client side :wink: