can you provide more information about which tests are you doing?
If i use the following pipeline:
gst-launch-1.0 -v filesrc location=/media/linaro/hdd-data/samples/big_buck_bunny_720p_h264.mov ! qtdemux ! h264parse ! avdec_h264 ! glimagesink
and if I try v4l2dec instead of avdec_h264, I believe I am getting better results.
Also, before running the video I did:
sudo cpufreq-set -g powersave
in order to force all 4 CPUs to run at 200MHz, instead of the default ondemand governor, which would make it difficult to benchmark.