I just got mine a few days ago, haven't had any issues with speed, writing, focusing, or otherwise....
For focus and shooting quick, i tend to shoot in MF and use the AE/AF button to quickly get it close and adjust from there.
Using a UHS card from sandisk, writing raw+jpeg is plenty fast.
I don't use the quick start, just half press the shutter every few minutes to keep it from going to sleep.
One funny thing, after many stints of street shooting with big bulky DSLR's and even with Medium format, never an issue, I got my first threats of violence the very first day I went with the X100. Ironically, the guy was wearing a 7D around his neck telling me it's illegal and creepy shooting portraits of people in public, demanding my camera, my memory cards, deleting all my images, etc...He finally left after I agreed to his suggestion that we find a cop and said please do so everyone watching can confirm him stating he's gonna punch me in the face several times....

I shot around 500 images yesterday, a little bit of chimping and the battery was still reading full when I got home.
http://www.flickr.com/photos/dizzyg44/sets/72157627110014688/