Running at 1600 by 900 resolution on a modest system. The performance is unfortunately halved by the video capture software I use. Without the video capture software running in the background the program runs at an average of about 10 frames per second.
The scene comprises the same test scene as in the previous version. There are two improvements over that version however: 1.) The mirrored sphere now reflects the glass sphere properly (no longer black). 2.) The frame rate is much improved.
There are three reasons I am no longer worried about the frame rate, at least for the moment: 1.) The way I plan to implement non specular lighting in the future will hopefully be quite a bit faster than the current method I am using. 2.) My system is a modest one. 3.) Improving the frame rate is no longer a priority and I suspect that my code can be made more efficent later on.
In my opinion the next priorities are to include focusing of light by the glass sphere onto the floor below it (caustics), and ambient lighting (e.g. walls reflecting light onto other objects). These effects should complete the photorealism of the image as, thanks to the method I plan to use, they will come hand in hand with important effects such as soft shadows and anti-aliasing.