In my (not so huge) coding experience, I've always noticed that code typing is the least time consuming aspect of a dsp project. To figure out a good concept takes longer. Testing and bug fixing takes longer. Optimization takes longer. I've once written an optimized FFT lib (in C). It took me a month if I remember well, and that was not because of all the code typing.
I wish I could code an external like he's coding: http://vimeo.com/36579366