Not Drawing uneeded

Hope you not making a 2d map in 3d this way only.

If you are doing a blockbuster. why not use sevveral small 32x32 sized squares. (aka 4 vertices or 2 triangles per quad)

you can make em single surface too. that way it will save texture memmory and be fast.

a level can have like 3.500.000 squares of 32x32 pixels.