Lights that take a long time to warm up are more about establishing an arc or gas temperature for full operation. They still respond to power fluctuations more quickly than the time it takes them to warm up.
E.g. I have both fluorescent and HID lamps with this characteristic; they take a couple minutes to reach full brightness, but still will dim when a big load kicks on and turn off immediately when I flip the switch.
E.g. I have both fluorescent and HID lamps with this characteristic; they take a couple minutes to reach full brightness, but still will dim when a big load kicks on and turn off immediately when I flip the switch.