Can you confirm which version of Datazen you are running?
Also - you could try running two utilities on your Core Server through an Administrator Command Prompt on your database in case there is any fragmentation or slow indexes.
Assuming default location of C:\Program Files\Datazen Enterprise Server:
net stop datazenrenderingservice
net stop datazendata
net stop datazen
cd\Program Files\Datazen Enterprise Server\service
esentutl /d Data\Data
Datazen.Server.Service.exe /console /resetindexes /shutdown
net start datazen
net start datazendata
net start datazenrenderingservice
Please advise.
Cheers,
CM