In L6562AD PFC ckt , 200uF/450v Electrolytic cap at the PFC o/p takes longer time to discharge when we switch OFF the mains in No load / no lamp condition. .
Switching on the mains while Cap is discharging gives high voltage spike and also hissing noise which may damage our HID ckt.
The resistors used for the output voltage feedback will basically act as a bleeder.I think you can tune those resistor values to get a better discharge characteristics.