Kontace And Kopete Extremely Slow

Since two or three weeks, whenever I start kontact, the window shows up, but then kontact does not respond for 2-3 minutes. In top I see that it is calculating at full load :(:(:(. This is very annoying. Even worse, whenever I edit an entry in the addressbook, kontact becomes unresponsive for 1 minute or so, calculating at full load. The same is with kopete. This behavior suddenly started to appear after an upgrade from the kde build service repository. I run the latest kde 3.5.10 on openSuSE 11.0. Any help or hints are appreciated.