Stephane:
You could consider using a graphic LCD module that uses a serial data and clock interface. This can cut down the number of I/Os to support the display by as many as 6 or 7 pins. (7 if you just ground the -CS line of the display and maybe 8 if you can tie the R/W line to fixed write mode). On most of the parallel interface graphics modules that I have used it is possible to select serial operation by strapping a PAR/SER line and then what were the DB6 and DB7 lines become an SCLK and SDAT lines. You can choose to bit bang the serial data or you can find a derivative with a SPI type hardware implementation. I used a Cygnal part at 22.1184 MHz connected to a 128x64 graphics module in serial mode using the hardware SPI port. The SPI clock operated at 2.7648 MHz. I was able to repaint the entire graphics image in less than 7 milliseconds.

Michael Karas