The short answer is I used multiple hubs to split the resource load and help with device range issues. HubConnect was the key at first but later switched to Node-RED.
I have 3 hubs currently by location - C-4 Main Hub covers first floor and basement, C-4 Upstairs hub covers upstairs, C-5 "control" hub handles (or did) cloud apps like Alexa and misc stuff like Lutron etc as well as coordinating modes and certain virtual switches between hubs.
My current plan is to migrate off the C-4s consolidating all the Z-Wave devices to my new C-7 and migrate my Zigbee devices to my C-5 (since the ZB radios are essentially the same between models). With Node-RED I've been able to move all my rules off the hubs so am reducing hub resource usage even further.
