Comment 4 for bug 1300393

Also happening here using latest nvidia drivers (331.113), CPU usage of compiz climbs when using the TV out on my GeForce GTS 250. I've been using this setup for years and this high CPU usage making the whole Unity almost unusable is very recent, a few weeks at most.

Running sudo perf top -p $COMPIZ_PID:

Single monitor: (compiz cpu% in top is around 2-3%)

  21.40% [kernel] [k] _nv013274rm
   4.07% [kernel] [k] rm_check_pci_config_space
   1.26% libc-2.19.so [.] _int_malloc
   0.85% libc-2.19.so [.] _int_free
   0.68% libc-2.19.so [.] malloc
   0.65% libc-2.19.so [.] __memmove_ssse3_back
   0.55% libnux-core-4.0.so.0.7.0 [.] _ZN3nux18NThreadSafeCounter9In
   0.52% libopengl.so [.] _ZN15PrivateGLScreen17paintOut

Second monitor turned on in display settings (compiz jumps to 18%):

  13.20% [kernel] [k] _nv013274rm
   3.80% [kernel] [k] rm_check_pci_config_space
   1.44% libc-2.19.so [.] _int_malloc
   1.34% libc-2.19.so [.] _int_free
   0.91% libc-2.19.so [.] malloc
   0.82% libc-2.19.so [.] __memmove_ssse3_back
   0.59% [kernel] [k] _nv008722rm
   0.56% libopengl.so [.] _ZN15PrivateGLScreen17paintOut
   0.55% libc-2.19.so [.] __GI___strcmp_ssse3
   0.53% libnux-core-4.0.so.0.7.0 [.] _ZN3nux18NThreadSafeCounter9De

Cheers,