I saw in another thread that the release Z-Way binding has a performance issue especially on large installations. Perhaps that could be a reason? How fast are the z-wave devices to respond if you control them directly from zway?
In my setup my primary USB controller is a UZB stick and control around 30 z-wave devices and with the latest security enabled Z-Wave openhab binding I get very good response times, less than a second. I used to have a Aeotec Z-stick but it was the older version that didn’t support secure inclusions. If I were to buy a controller today I would probably get another Z-Stick since the UZB seems to give me less range than the stick.
I also use a Razberry and Z-Way server but it only controls 2 Danalock door lock devices. I have had lots of trouble with failed security negotiations jamming the openhab z-wave binding so I figured it would be best to run a dedicated network for those. It also allows me to keep the razberry right next to the door so it gets a good signal from the Danalock V3 which seems to have a rather poor internal antenna. If you have devices that require security maybe you should consider running several controllers too 