High CPU on latest nightly

[Kamil Paral]

> it's maybe not noticeable in a typical install, 

I have Core i7-2640M CPU @ 2.80GHz with 4 cores (2 physical + hyperthreading). If I run netinst in KVM with 2 virtual CPUs attached (I assign 2 cores instead of 1 to speed up the installation), my host performance is *devastated*. I can hardly scroll a web page in Firefox. Opening any application takes 5-10 seconds. The longer the installation runs, the worse it gets. If I use Live instead of netinst, everything is smooth and fast. If I disable the spinner animation using that updates.img, it's again smooth.

This problem didn't exist in F20 and prior. It appeared in F21.

I wanted to perform some measurements to have exact numbers (e.g. the length of an installation with and without the spinner, depending on the number of CPU cores assigned; gather some `top` statistics during the run) before reporting the bug, but I never got to it. Any help is welcome.