I use to use Z-Wave motions for this purpose. They were as you are experiencing, very slow to do turn lights on. On top of that, they had a 4 minute reset time before they would trigger again.
They were not doing what I wanted.
I just added a hard wired alarm system and interconnected it with my Vera Edge. Now I can use 15$ wired motions all around the home for both security and occupancy detection. It has sped up my on reaction time with my lights considerably. Usually (99% of the time) it is around a half second from the time my motion reacts to any movement, to the time the light is on.
With the reset time now at 0, I can turn the light on again at any time with the wave of my arm.
Upgrading your V3 to a newer Edge or Plus should help some but as I have never used a V3, I can not say. Maybe some more experienced users will chime in on that, but Z-Wave is still Z-Wave and you will always have more delay than any hardwired system.