I messed up ... with fft-js

[lpatiny]

Sorry I messed up ... it is not fft-js that should be used but fft.js. Small difference but @josoriom did a small benchmark for us:

fft.js is 120 times faster !!!!

@djeanner could you try to use this other library ?

https://github.com/indutny/fft.js#readme

[lpatiny]

closed by 6129e99705e607bb8446a5202ba0c5f6a1fa235e