Blender getting very slow in handling large data? I have a scene having 54000 planes in it. Blender is responding very slowly to the actions performed on this scene. Even the simple view changing operations done using middle mouse button are responding very slowly. And when i try to render them , blender stops working.

I think this is happening because of such large no. of planes having no connectivity between them at all, but 54000 planes is a very small number. 

Can anyone tell me the exact reason of this problem and how to correct it to make blender more responsive with so many no. planes?
The answer to the question you asked is that 54000 individual objects is significantly different from 54000 polygons, so it's not surprising that Blender is having trouble with that many individual objects. There are some ways to improve viewport performance like turning on VBOs in the user preferences, but I don't think any of them will be terribly helpful at this point.

If all the planes were joined into one object, it'd probably perform much better, but it doesn't seem like that would be very helpful, for what you're doing.

The answer to the question you didn't ask ;-) is that this is a really expensive way to render a point cloud in Blender. There are two tools that will probably be very useful to you. One will get point clouds into Blender, and the other will skin point clouds in Blender. And this will probably be much more workable than your current solution ;-)

Hope that helps!