brumd: For a moment I thought the firmware-upgrade also dramatically improved the long writing time.. then I realized I had to switch it back to capturing RAW :/
This long time in which it is impossible to change camera settings, for me, is the only real issue with this camera. If only settings could be changed during the writing time.Otherwise, this firmware upgrade is really great. I love to have easy access to the ND-filter, and the dramatic improvement in autofocus time is awesome!
I believe it is the speed of the SD card you use in your X100 which speeds up or slow down the X100. After upgrading my card to an Sandisk Extreme Pro (45 MB/sec) the X100 is noticeably faster.
Another problem is reading the card with an iPad for example (with Camera Connection Kit) and putting it back into the X100.
The ipad is putting some information on the card which slows down the start up or writing of files to the X100. If you "write lock" the card before reading it with the iPad or reformatting after uploading the pictures, it is fast again. Weird.