You are free to create your own build of RightJS, which best fits your needs.
To create the builds we use Front Compiler, the most effective JavaScript compression library written in Ruby.
The self-building feature creates self-building javascript code, which reconstructs itself on the browser side. It gives you an additional 25-30% compression, but in exchange it takes about 5 to 100 ms for reconstruction. The exact duration depends on the browser and hardware.
For most real life applications it is practically not noticable to the user, but if you are creating an extremely light-weight application and care about user experience you might consider turning this feature off.