Scaling of the point sprites

Hello dear friends. Tell me please what values should ​​I set for D3DRS_POINTSCALE_A, D3DRS_POINTSCALE_B, D3DRS_POINTSCALE_С to point sprites scaled just like other objects in the scene. The parameters A = 0 B = 0 and C = 1 not suitable because the scale is not accurate enough and the distance between the particles (point sprites) can be greater than it should be. If I replace the point sprites to billboards, the scale of the particles is correct, but the rendering is much slower. Help me please because the speed of rendering particles for my task is very important but the precise of their scale is very important too.

P.S. Sorry for my english I'm from Russia