Markus demonstrates his OLED display sine-scroller:
The OLED board sold by SeeedStudio used I2C to communicate with the MCU. I found that updating the screen this way takes too long to get a descent refresh rate, so I modified the board to be able to access the driver chip using its SPI interface.
Updating the whole screen (128 x 64 pixel = 1024 Byte) takes now only about 1 ms, giving enough time to do some other fun stuff between updates :)
Thanks Markus! Via the comments.