On my system with WinUAE 2.4.0 PB 15 with a 68020 cpu.
Speed test for FFT + iFFT: (float)
time needed 644ms for 413696 samples, => 7.28327751159668x speed @44100Hz/stereo
Speed test for FFT + iFFT: (integer)
time needed 644ms for 413696 samples, => 7.28327751159668x speed @44100Hz/stereo
Speed test for FFT + iFFT: (integer handoptimized 68K ASM)
time needed 267ms for 413696 samples, => 17.5671558380127x speed @44100Hz/stereo
