If you use Z-Wave on C7 and have not updated yet, I highly recommend running the update.
We have seen dramatic improvements in Z-Wave stability and performance.
Upgrading to 2.3.1 is not enough, you also need to run the "Firmware Update" through the Z-Wave Details page.
Not sure if your hub is running the new firmware? Visit the following endpoint to check the version that your hub is currently running:
http://yourHubIP*/hub/zwaveVersion
*replace yourHubIP* with your hub's actual IP address.