Hi,
For a stored procedure group, I really don’t think it should take very much time to start. The group must make a subscription for opc, and then add the items, but otherwise it doesn’t have to do much else. That process might normal take 500ms or so, though it can definitely depend on the OPC server. It is possible that your opc server is trying to validate all of the items during that startup, instead of accepting them and sending bad quality later.
Did this problem start recently? Did the OPC get upgraded? If not, perhaps some devices are offline, and that is affecting other devices? OPC servers usually only use a few threads, and service the various devices in turn. If one is responding slowly, that can block operations (such as subscribing) for other devices.
Regards,