Use instancing / BufferGeometry for better performance

[Rohan Deshpande]

As highlighted here, there's too many draw calls happening, which causes a performance bottle neck.

We can have a look at the following examples to get this going

• https://github.com/mrdoob/three.js/blob/master/examples/webgl_instancing_suzanne.html
• https://threejs.org/examples/webgl_buffergeometry_instancing.html

[Rohan Deshpande]

Resolved by #89