I’d enable zwave debugging first and watch messages to find if there’s messages getting lost and where the delay really is located.
If I was to take a guess then its that your zwave mesh is bad. Use habmin to see your shutter node’s neighbours and try to heal that node.
Eventually move to the dev binding - unlike the 2.3 version, it’s healing the network once a night and comes with a feature to handle Fibaro proprietary messages.
