Compared to JNTFFT, ACM's unidimensional FFT is slower.
Benchmark and results coming soon.
Ok, that was a quick one : my tests had been done last december with a snapshot version of Commons Math.
Now with the official 3.0 release I'm finally getting performance numbers similar to JNTFFT.
So I'll close this ticket, thank you guys.
Report was based on a pre-3.0 snapshot.
All is fine in the official 3.0 release.