Adafruit's 32x32 RGB LED matrix panel

The difference is that the 16Mhz Arduino was programmed using inline assembler (if you look at the library source) rather than in JavaScript :)

Having said that, you could:

• Compile Espruino with your own C function that would clock out the 6 bits of colour required.
  
• Write some inline assembler for Espruino to handle it in Espruino, using the nativeFunction call that'll be appearing in 1v60.