That's a reason why he ask us a help, so what you must to do is:
1.Make it not flat anymore, do the best you can
2.farZ make problem? reduce your sight range make you only see nearby and cause system didn't read unit outside your sight, might reduce lags slightly
3.Why it's unusable? all MMO-RPG game use camera like this, not bad to do this in war3 maps
4.Like i said at 2, reduce sight range to 600(smaller is better).. Make lag reduced
HappyTauren please don't crush his dream with your 4 reason, the number 4 is as the same as number 2 so you must make it simpler. ONLY 3 REASON