Image too large

What i have is a very large image, approximately 9000x9000

what i was hoping to do was to cut it up into 9 smaller images 3000x3000
or 18 images 1500x1500 for performance purposes. (so not all images have to be displayed at the same time, as you walk in a game)

My problem is how to now apply these smaller images to my single large mesh as individual small images.

My hope was to apply it to a number of empties at the right location so it would look like one large image. But if i map it to the empty, i cannot map it to the UV coordinates as well.

Is there any method for applying small images so that they still take UV coordinates, and line up looking like one image?

What about dividing the plane into as many faces as you have images, and map each image to one face?