Johan:
You say that it would take a lot of FLASH storage space to pre-store many pictures that are used on the display.

Just how is the current product configuration synthesizing these "pictures"?

Wouldn't it just make sense to slice out the display driver part of the current implementation, including the picture generation, and move that to another MCU and then put an interface from the main controller to the new display controller. If I were doing this I think that my preference would be to couple the two CPUs via a hardware peripheral fast SPI connection.

Michael Karas