grand theft auto V like far light flare solution?

link text upon is the link in grand theft auto V game play,when he was in the sky looking at the city , i figured that all the spotlights would be rendered as a billboard? a tiny little pixel with some halo,as we all know that actually these far lights have already been culled but the flare stay on the screen. and as u walk next to the spotlight, the flare would fade away ,and when u got away from it, it actually stays the same size.

so i thought that maybe they use the sprite billboard without scaling itself by the distance change ,when the light r too far away from the camera.

so would anyone know how to get the code done ? consider that there will be 10000 billboard in the cam , what is the most efficient way to achieve this? i looked into the "look at " method is not that ideal ;