So I've almost finished up the shadowing aspect for the new release, and I even have a few numbers to throw around in regards to multi-light performance.
The above screenshot shows that multiple light shadowing is now added. Now depending on the actual light you want to use in the room it has a big effect on the quality of the shadowing. In this example I'm using "ceiling" lights that have a close to 180 degree output of light, pretty much like you expect ceiling lights to have.
However the wider the range of light that comes out, the more pixelated the shadows become. If you use targeted spot lights you will find the shadow quality to be extremely high. It will be up to the user to decide what kind of lights they want to add and how they want the room to look.
This screenshot shows that with 10 lights casting shadows I'm still getting over 100FPS @ 1280x720 . There is still some vast improvement to come. At the moment I'm calculating shadows every frame, however they don't necessarily need to be updated every frame unless objects are moving every frame.
I've also optimized the lighting engine itself, improving the efficiencies of the shader code and also adding some macro features. So there will be performance improvements over the last version too if you don't want the newer accurate method.