i fully charged the battery and had a look with "top" at the cpu usage every half hour. (unlock phone, start x-term, top, close x-term, lock phone)
and my battery is empty after 24 hours.

and i have to say:
the xorg log process is constantly running with about 4% cpu usage... and the other processes ALL TOGETHER with about 4 %...
so in my opinion the 4% are way too much for one process.
if this process would just use as much as the other (single) processes my battery would last TWICE the time it lasts now!!!