I would suggested finding a controller for it. It will relief a lot of processing from the CPU. OKI and Rohm used to make them. It has been a while since I look at those. Why do you want to use a graphic LCD without a controller at the first place? With a LCD controller, even a 8051 will seem very fast.
NEVER REINVENT THE WHEEL !!!!!!!!!!!!!!!!!!!!!!!!!!
Except if your main target is to make a graphic LCD controller, i really advise you to get a module with a built-in controller chip. It will save you a hill of a headache. I strongly recommend a T6936 based one, since it accepts mixing graphics and text on screen easily.
Try Motorola DragonBall series (68K or ARM core):
such like as MC68EZ328 (68K core), build-in LCD Controller
(software programmable up to 640x512)
and the list price is under U$5.
If you need more performance,
try MC9329MXL/MC9328MX1 (ARM920T core),
list price will be under U$10~15.