Would it be better to use a 128x128 sprite to make grass, or to make a 4-poly model, and apply the 128x128 skin to it. I understand that either way, a few will not impact my preformance, but I am talking about placing hundreds of these in groups. In the long run, which is better, very low poly modeling, or a sprite? Thank you.

Rather than a bunch of models or sprites, have them in bands in one single model. For best performance and the most detail, have your single model between 2000 and 5000 polygons. For 2000 polygons, you could get 1000 "ribbons" of grass. When criss-crossed, by duplicating the model, you could have enough grass to cover a 250x250-foot area when each ribbon is spaced 4 quants apart with a 16 quants per foot map scale. With such a setup, you could get 100 times the rendering speed than if you used tons of sprites or low-poly models. Want an example of this grid design?

haha, thanks ulillillia, I have seen ur performance chart before, so no need to show it again . It will be a little harder, because I will need to plan out where I want the grass, but yes, sounds like a solution. I will go with that, thanks.

Ah, for knowing where things are, just open the file you want to put the grass on to, save it under the grass name you want as a temporary file, then, from that, just put the grass where you need it then deleting the ground for the main file to be used.