High CPU usage with nautilus and sometimes gnome-shell

[Usama Akkad]

Hi,

This is my first message to this mailing list. I hope to helpful 
responses from this great community.

I'm using ubuntu-gnome updated to the latest version, I'm having problem 
that prevent me from using nautilus. When ever I open any nautilus 
window that have anything with thumbnail it will increase my computer 
fan speed directly with CPU usage hitting between 10-50%.

Another problem that I have is that sometimes gnome-shell reach 90% CPU 
usage and I should kill it then run it in order to things to work 
normally again.
My graphic card worked perfectly on on Ubuntu 14.04 LTS with gnome-shell 
from gnome ppa

Ubuntu Gnome:    15.04
Gnome Version: GNOME Shell 3.14.4

Could someone suggest a fix for these two issues as I've searched a lot 
but couldn't get an answer.

Thank you,
Usama Akkad