Those Zen25 are known troublemakers, especially when configured incorrectly. They can bring the hub to its knees. They are very likely why you are seeing lags. Personally, I would get rid of them, they belong in the "drawer of shame".
With that being said, some have had success by adjusting the parameters a certain way, Some Zwave devices are intermittently slow or non responsive so - #30 by jtp10181
I also would be sure that you are on the latest plug firmware ZEN25 S2 Double Plug Change Log - Zooz Support Center
