I’m sure that’s very frustrating. We need to do a little detective work first. Let’s leave the zigbee bulb out of it for a minute.
A) If You’re saying that you have a GE zwave loadbearing switch installed on the circuit that controls the light fixture and flipping the switch manually has a delay In the light coming on, then that’s a problem with either the switch or the wiring, because the switches work manually at the wall even if your hub is missing all together.
B) If instead you’re saying that when you flip the switch at the wall the ceiling light comes on immediately, but if you tap the switch tile in the smartthings mobile app there is sometimes a noticeable delay before the ceiling fixture comes on, then the problem is again either a defective radio in the switch or the mesh is weak and the messages are not reaching the switch. ( or maybe there sometimes local interference.)
C) If you’re saying that when you flip the switch at the wall the ceiling light comes on immediately, but it takes a few seconds for the status update in the SmartThings mobile app, then that’s a different issue.
I’m very tired today, so I’m going to have to leave it to other people to continue with this, but based on the answers to the above three questions if it looks like a mesh problem your next step would be to do a Z wave repair.
Again, leave the issue of the zigbee bulb of out of it until you have the speed you want for just tapping the switch icon in the SmartThings mobile app and turning on the ceiling fixture.
Then you can look at the speed of just tapping the bulb icon in the smartthings mobile app and start from there on the bulb. But first get the switch itself up to speed. Then get the bulb up to speed. Then start working on the combination.