As some have noted, we use a very special way to update our screen. I thought I could into some of the details about that.
Most projects with small screens use an interface like composite or SPI (PiTFT for example) because that is much easier to setup and use very few GPIO pins. The problem of composite is that it is not very sharp and the problem of SPI is that you cannot output the GPU directly to it so you have to use software which introduces some lag.
In our project we use the HDMI/DPI mode which enables us to have a very fast output with no CPU usage.
DPI is awesome
The main reason is because it’s wonderfully stupid.
Thanks to the work of [Robert Ely], [Gert van Loo], [Dom Cobley] and the advice of [wpt-nathan], we were able to configure the interface in RGB565 which leaves us eight pins for SPI, the buttons, the backlight and PWM audio.