Lag from Map Wall Glitch

Put the summary of the bug you're having here

What I expected to happen was...:
Maps load normally

What actually happened was...:
Maps appear to be loaded in, however if you are looking at the map wall and look away there is horrendous lag until you face away from the maps.  This happens within about 50 blocks from a map wall.

Steps to Reproduce:
1. I have 2 x map walls of the realm to level 3/4 to + and - 6000.  This is 144 maps on each wall.