How to speed up the startup process?

Please uncheck the “Validate items” check box in the “Advanced Settings” dialog. 

Select in the navigator control on the left side of the Configurator main window the section Settings -> Advanced. In the dialog window you will find the mentioned check box “Validate items” below the section “Global DS-OPC and DS-Tunnel Settings”.

This entry decides whether the item IDs from a dynamic server connection subscription should be validated or not. If no validation is performed all item IDs from the subscription file will be accepted by the local dataFEED OPC Suite application for a dynamic source. 
Leaving out validation increases the item adding speed.