[koper89]

I tested few options and f.e. when I download something using rtorrent with xbmc in screensaver I can't get more than 3,2MB/s download (still not bad)
But when I turn off xbmc, I can get 5MB/s download speed (it's a maximum value of my ISP, so i suppouse it could go even more)

I just started vmstat so I'll post it in about 2 hours.
Best wishes

EDIT:
I discoverd that one I'm in "screensaver" mode the Nicelevel is indeed what i configured in /etc/default/xbmc but when I try to check if upstart xbmc-screensaver is on i get: stop/waiting
I checked this because I tried to use script from:
http://forum.xbian.org/thread-2040-post-20131.html#pid20131
but it doesn't seem to work, I have him on my upstart list: initctl list but still it's not disabling my xbmc.