System extremely slow under light load

[Bartosz Fabianowski]

This appears to be a different issue from the one I am seeing. The 
system is very responsive at first and only under load (and with rising 
temperatures) becomes extremely sluggish. As load (and temperatures) 
drop, the system becomes usable again. Also, there is no difference 
between Qt and Gtk apps. All of them are equally fast or slow.

- Bartosz