After seeing FPS drop whenever I flew over farm tiles I decided to do some test using a single large airfield surounded by a single tile type, test were done at 1600 x 1200 all sliders maxed out, in the tower with clipboard up on a TI 4200 8X AGP. Here's the results.
Grass---------------86
Grassy Rock--------82
Farm----------------41
Rock----------------75
Forest--------------67
Snow---------------96
If anyone is getting different results with other types of cards please post your results here.
