Blender gets very slow to draw a scene having large number of plane? I have a very simple python script to generate planes in the scene. I want to generate 50000 planes in a scene, to compensate for unavailability of POINT primitive, so that i can render a point cloud. 
It runs at a good pace till 2000 th plane is added , then starts slowing down, and gets very slow.
My computer's config is - i7 3.4 GHz, 16GB RAM, GeForce 9800 GTX graphic card.

here is the python script-

import bpy 
from math import *
import random

for i in range(2000):
    x=random.uniform(0,100)
    y=random.uniform(0,100)
    z=random.uniform(0,100)
    bpy.ops.mesh.primitive_plane_add(location=(x,y,z))
    #bpy.context.active_object.scale=(100,100,100)
    print("\n",i)


Any Help on 
why it is slowing down?
How can this be fixed ?
Any alternate approach to render point cloud in blender?
would be much appreciated...

Thanks for your time and attention
Dupli objects
Try using Dupliverts (instances):

Create/import the point cloud as a mesh with only vertices:


Create a single tri by adding a plane (ShiftA&gt; Mesh &gt; Plane) and merging one edge with AltM:
 

Parent the tri to the point cloud by selecting both objects with the point cloud active (last selected) and pressing CtrlP.

With the point cloud active, enable Verts in Properties &gt; Object &gt; Duplication:


Add a track to constraint to the tri with the camera object as the target so that all the tris face the camera:



This has performed fine for me with point/vertex clouds of over 7000 vertices.
This will work with both BI and Cycles.
Halos
Another method for rendering point clouds is to use a Halo Material:

Create/Import a point cloud as vertex only mesh (no edges or faces):


Create a Halo material:



Note that this only works for BI.