I bought a couple of Diavolino boards to make some funny project! I also bought FTDI Friend from Adafruit. Everything works well under OSX but the sketch upload is much slower than Arduino Uno board (wich have an onboard USB interface).
For a complex sketch 12 secs are required for upload on Uno, while Diavolino + FTDI requires 26 seconds.
Can you please say exactly what you are trying to do, and what your configuration is?
For example, which ports on the Diavolino/Uno are you connected to, and are you trying to upload a program, or trying to write the bootloader?
The reason that I ask is that you normally care about *either* the listed serial port (which is used for normal “arduino style” programming– through the serial port of the microcontroller) OR the programmer listed in the Programmer menu (which is *only* used for bootloader burning, through the ISP port of the microcontroller).
If you are using these things in the “usual” way– through the serial port and not the ISP port –then the speed difference is natural, and a fixed property of the board type. The Diavolino is a derivative of the Arduino Duemilanove, and (for compatibility with the Arduino application) has the same upload speed that it does. You can in principle change this speed to be faster, but you’ll also have to change the bootloader to match.