Autofocus in live view is unbearably slow
I've tried AF in Live View, and I have experienced, that sometimes the D5100 does the usual focus cycles before locking on the subject in the rectangel, BUT... sometimes it is starting to make a weird and sharp buzz sound, and the AF speed is greatly reduced during this kind of action. It is really annoying, and I'm afraid it is greatly mistreating the SWM in the lens. How can I report the problem to Nikon?
I am using a 18-105 VR lens on the D5100.