Comment # 17 on bug 83436 from smoki

 OK i found -mtune=generic is culprit for performance :). Played a little with
-mtune to found what is minimum this code wants to work fast:

 -mtune=i586 = slow
 -mtune=pentium = slow
 -mtune=pentium-mmx = slow
 -mtune=pentium-pro = fast
 -mtune=i686 = fast
 -mtune=pentium3 = fast
 -mtune=pentium-pro = fast
 etc...

  So -mtune=generic seems to set lower cpu target than this code needed to
perform fast.