https://bugs.freedesktop.org/show_bug.cgi?id=50657
--- Comment #6 from Thomas Lindroth thomas.lindroth@gmail.com 2012-06-13 06:56:07 PDT --- I've figured out what cause the performance increase. When dmesg gets flooded with messages syslog use 100% cpu for a while. Performance increase during that time. The same thing can be achieved by running while true;do true;done. I guess it has something to do with the cpu's power states.
It would be nice to always have that boost. Using fthrottle_mode=0 didn't help.