Looks like your video card is overheating from stress, old drivers, or overclocking.
Since you have lag, you may be underpowered. Can you post your system specs?
Try lowering all of your graphics settings to low or off. Then try lowering your screen resolution as low as it will go and maybe it will become playable once more.
As I keep inspecting I find that this is a problem caused by clouds, is there a way turn them off?