Hi we are just discussing FFTW in our institute and we hit this bug reported to Ubuntu which also holds true for Debian: https://bugs.launchpad.net/ubuntu/+source/fftw3/+bug/602586 Is there a specific reason why SSE is enabled for 32bit and not enabled for 64bit as the difference in performance can easily be a factor of 2 (on 64bit). As this is very often used in science, I thought people might know why this was chosen. Cheers Carsten