http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55065 --- Comment #3 from dschinn1001 <cv.schmitt at gmail dot com> 2012-10-25 12:16:24 UTC --- sorry for my inconvenience - it is simply the difference between USB 2.0 port and USB 3.0 port ! It makes with the test-code above a difference of 1 Kibi. Regards. dschinn1001