I have one working and it doesn't lag or glitch at all. :/
Zones are a lot better for vehicles. Vehicles could bump ub and down on roads, this could be why it sometimes doesn't work.
The bigger problem is the detection for vehicles is hacky at best... or so I vaguely remember. People made hacky methods to detect it, I think.
ZoneEvents do not use raycasting. Each zone consists of 1 Torque game engine Trigger and 1 Physical zone. the Triggers in the zones have a 200ms refresh rate.