I just installed F18 alpha and did an update. I run evolution which is using gcr-prompter for password prompts and I realized one of my core is busy. 'top' showed that it's XOrg and gcr-prompt making it unhappy. This is both with gnome-shell and fallback mode, while with gnome-shell also the gnome-shell itself adds itself to CPU eating, thus it looks like two cores are busy, while the UI only waits until my password prompts is finished. My simple test showed that this is something with UI, because if I switch to a terminal (Ctrl+Alt+3), then the CPU is happy again, while going back to graphical UI CPU usage goes immediately up again. Another test with the Spinner gtk3-demo shows that it does it, the spinner causes high CPU usage. This is with gtk3-3.6.0-1.fc18
One more note, staying in GUI and moving to other Workspace (fallback mode) doesn't help with CPU usage decrease, one might move to text console to let it be low.
This should be https://bugzilla.gnome.org/show_bug.cgi?id=684639 which is fixed in GTK 3.6.1 - it will be in updates-testing soon together with the rest of GNOME 3.6.1.
Thanks, I'll check it out as soon as it'll be available in updates-testing.
It's better with gtk3-3.6.1, but still unacceptable. The spinner demo eats about 8% of CPU when the two spinners animate. The gtk3-3.4.4 eats none CPU when animating the spinner. I'm moving to the upstream bug report.