I use fedora 22 64 bits.
I installed a cpu monitor on my desktop.
Each time I installed a frequently refreshed widget on my desktop, the CPU load rise to 100%.
Once I removed to widget, the CPU load goes back to normal.
Sounds like duplicate of https://bugs.kde.org/show_bug.cgi?id=345696
Yes, it's a duplicate of this bug report. Sorry.
*** This bug has been marked as a duplicate of bug 345696 ***