Hi there. There are many reasons why a lock may be unresponsive or slow to respond. The type of lock and module have a role to play but more importantly it’s usually an indication of the underlying mesh or/and ghost devices which may be interfering with you setup.
You may want to read through this blog from @RBoy on how to optimize your mesh and weed out any ghost devices. FAQ: why would I need another beaming repeater if my zwave lock is already close to my hub?
As for the device itself, the Kiwkset 916 is a popular model but has a few quirks. You can find out more details on this topic first post, look for the link about lock limitations which explains how different models of locks behave in various environments: [RELEASE] Universal Enhanced Z-Wave Lock Device Handler for Schlage, Yale, Kwikset, IDLock, Popp, Danalock, August Pro, Keywe, Philia, Samsung
It’s good that you have many mains powered device close to your lock, with the new IDE tools you can even look at the z-wave statistics to see how the lock’s zwave module is responding to the mesh.
Device handlers play a key role in access hidden features within a lock, optimizing the lock behavior and in some cases providing workaround for bugs in the lock’s firmware. You can also find more details about these in the Universal Enhanced Z-Wave Lock device handler page.