* Don't use double precision unless you're absolute sure you need it.
* Compile the FFTW library (yourself) with the correct flags on x86 (in most
cases, the correct flags are automatically configured).
-* On x86, use gcc or icc as the compiler (not pgi or the Cray compiler).
+* On x86, use gcc as the compiler (not icc, pgi or the Cray compiler).
* On POWER, use gcc instead of IBM's xlc.
* Use a new compiler version, especially for gcc (e.g. from version 5 to 6
the performance of the compiled code improved a lot).