Sony recently released un updated version of the firmware for the DSC-RX100 camera. According to Sony, the new firmware, Version 1.10, improves the operation of the autofocus mechanism to reduce noise and vibration during focusing. Here is a link to a page where the updated firmware can be downloaded; instructions for installing it are provided there also.
I have not used this update myself, because I no longer have my RX100 camera. It sounds like a worthwhile upgrade, though.
For general information about the RX100, see the guide book available through this site and from other sellers.