Simple questions about CUT_DEVICE_INIT

In multiGPU, do we need to CUT_DEVICE_INIT after each setDevice or is it only possible
to put it one time at at the start of the main (I see no difference except When I put it each time, it takes more than 2 seconds!)?
Does CUT_DEVICE_INIT initialize all the memory of the card, or is there a way to do it?

My config: XP+2GTX295.

Thanks in advance