Here is a summary of FFT performance.
Full timings for all NAS VSIPL routines below:
VSIPL Performance on Atom N270
VSIPL Performance on Xeon X5570
AVX Optimisations and Case Studies:
AVX Performance Gain Study: SARMTI
Image Signal Processing Performance on 2nd Generation INTEL® CORE™ Microarchitecture
AVX2 Optimisations