How to optimize?

I have build my terrain map using octree using the models from 3DS Max. How can I optimize the speed in drawing? I got my own file format, all the polygon meshes that are connected and using the same material is stored in an array. But because of the octree structure, I need to send the polygons according to the travesal of the octree. Should I make a list and sort all the polygons first before drawing or just send the polygons directly from the travesal? Or should I even sort all the poylgons with the same material first no matter they are connected or not?