gazebo immediately causes nearly 100% CPU usage, even though I have no models loaded and have the simulation paused.
top shows, on average, that the CPU usage breaks down like:
80% /usr/bin/gnome-shell 60% gzclient 20% Xorg 10% gzserver
Obviously, the big offender is gnome-shell, but as soon as I quit gazebo, gnome-shell CPU usage drops to 3%.
My system is a dual-core Macbook Pro running:
Ubuntu 12.04 OpenGL 3.3.0 (NVIDIA 331.113 driver) Gazebo 4.1.1 (installed from the "Step-by-step" instructions at http://gazebosim.org/tutorials?tut=install_ubuntu&cat=installation)
Another odd thing I've noticed, is if I set "shadows" to "false" under World->Scene, then CPU usage immediately drops, although is still a bit high. The break down is roughly:
20% gnome-shell 20% gzclient 10% gzserver
However, the if I click away and then back to World->Scene, the "shadow" value is reset to "true".
This seems related to my graphics driver. If I install gazebo on another 12.04 machine, but running OpenGL 3.0 (Mesa 10.1.3), gazebo runs fine with almost no CPU usage.