If you have unlimited storage like that, you might want to reformat the data to a form optimised for display. I'm not sure of the way your LCD is spoon fed pixel data (vert? horiz?) but I would make a file format for the graphics with the pixel rows/columns formatted the same way for very fast display.
thats exactly what i have done heh... since i write from Left to Right starting at the top... my converter converts the images into binary data where once i open the file i can take a chunck of 2000 bytes and spit it to the LCD without any work ... (only shifting it since i have the LCD lines split up into 2 parts)