I should learn to leave well-enough alone. When I moved to Hubitat 2 months ago, I added the z-wave poller app and started polling 2 "problematic" GE z-wave switches.
I noticed that occasionally (maybe a few times a day), my HE would stop controlling z-wave devices, or respond very slowly to manual control of z-wave devices (outlets/switches/dimmers), but zigbee and lutron control were never slow. So it wasn't a general hub slowdown.
Last week, I started z-wave polling every available z-wave switch and dimmer, hoping to remove this occasional slowdown, and noticed that the frequency of the slowdown increased dramatically. I tried rebuilding the z-wave network several times, removed sensors, all matter of nonsense.
Today afternoon, it struck me that maybe z-wave polling was the problem, so I removed that app. Hub slowdown disappeared. Everything is back to being super-fast.
Maybe I set something up incorrectly when I setup the app.
I had a non plus GE switch that I set up with the polling app. The switch was always out of sync so I just decided to move that switch to a non important location and remove the polling app.
Glad to hear things are working better for you. I see you removed the app as a troubleshooting step. It is also possible to disable the app. (Recommended as a first step so that if it is not an issue you can re-enable it. Saves some time.) Since it is a bit hidden I have included a couple screenshots.
My non-plus devices are four GE switches, two GE dimmers, a MIMOlite, seven Leviton outlets and several contact and motion sensors. Too many to replace at once. But over time, I'm planning on replacing them with plus equivalents.
I may look at replacing a couple of other devices that aren't plus as well but for now, things work well. For the most part, anything that isn't plus is only operated via automation and they stay synced.
Oddly enough the two GE switches that were problematic - and made start using z-wave poller now fine work. In the interim, I had added four Aeotec range extenders to help with my Schlage locks.
So maybe I should heed my advice, and leave well-enough alone