change Tempo effect like Audacity's

[wis]

First of all, This is an awesome web app and project really shows the power of the web/web-audio and shows-off your skills.

The Tempo effects differs from the Speed up/down effect by the fact that it does not change the tune, only stretches the selected audio, the algorithm works by adding silence bits when leaving the "Use high quality stretching (slow)" checkbox option unchecked and when it is checked there are no silence bits when stretching short selections by a big factor.

Have you though about or researched if WebAssembly could be used in order to reused already implemented c++ algorithms for effects without re-implementing them in JavaScript?