Mythtv, vdpau and cpufreq

Since the GPU is performing most of the work in decoding videos, the cpufreq daemon does not increase the frequency and the bus clock is too slow for certain playback (bluray, SD tv with advanced filtering). I add two lines in screensaver-x11.cpp to force the cpufreq daemon to go in performance mode when playback is running. I go back to normal when playback is not running.
I used
#include

system("cpufreq-set -g performance");
and
system("cfupfreq-set -g ondemand")

near the lines with the DPMS messages ...