Matt, over at Raspberry Pi Spy, has blogged about a way to improve the performance of the I2C bus on a Raspberry Pi. The bus, which is used for, among other things, sensor readings and outputting to OLED displays defaults to 100Kb/s but can be made to go as fast as 400Kb/s by changing a value in /boot/config.txt. This can improve performance for some applications. For the full details, head over to this page.