If you have used an iPad SD card adaptor to review images taken on a Fuji {X100}, then you may find that the camera is slow to respond or wake from sleep. In my case, I thought the camera had broken as it took 30 seconds to display any data after being turned on, but it turns out that the iPad had created a folder in the root of the SD card, and it was this that was the culprit.
In short, switch the SD card write protect switch to the Lock position before inserting it in a USB card reader or iPad adaptor and nothing can interfere with the camera formatting, preserving the normal operating speed.