Unity consuming 100% CPU

That is a well known bug and I think I saw some progress on it. Actually, I don't think I've experienced that in a while. Make sure to install the newest upgrades. It might have been fixed. If not, until it does get fixed, you can easily "fix it" by pressing alt+f2 and typing killall unity-panel-service. This will restart the indicators and it will be back to normal.

Unless you want to actually fix the code, there is nothing you can do to prevent it, save add some information to the bug report.

Another possible workaround is limiting the CPU usage of unity-panel-service. You can download a simple program called cpulimit with:

sudo apt-get install cpulimit 

Then you can run this command:

cpulimit -e unity-panel-service -l 30

It does not fix the problem, but maybe makes your system usable while the proper fix is released. As Jo-Erlend Schinstad said, it's an old bug. I suggest you report it also affects you at:

https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1199877