The running time consuming so long!! Plz help!

[SteveTanggithub]

my config: n_mel=128,n_fft=2048,n_hop=256,sr=16000
it takes about 20 second for getting melspectrogram from 8 second long wav file!!!
Is it normal for this code?

[ewan-xu]

eigen fft is too slow. You can replace with other fft . e.g. fftw.

[SteveTanggithub]

i don't know how to use, can u help me?
by the way, it also takes too long (17s) when i use eigen for matrix multiply.
(128,1025) x (1025,501)