This is an easier to get installed z-wave mesh network graph:
Network healing should occur every night by default. So it is unlikely to help without relocating or adding a few devices.
The other thing to check is your OZW log (bottom of the integrations page). It’s a pain to read but may show a sensor is spamming the network and slowing everything down.
On a small network with 6 devices mostly connected directly to the zstick in a raspberry pi I never got switching latency lower than 3-4 seconds. I’ve since moved to wifi devices and find the latency less than a second.