If you are still running version boinc-manager-7.6.22-4 on Fedora (22, 23, 24) you might be willing to upgrade to 7.6.22-6.
Reason: 7.6.22-4 has created a file in $HOME/.BOINC named stderrgui.txt that's growing rapidly. This also means it's eating CPU time.
See https://bugzilla.redhat.com/show_bug.cgi?id=1347423

You can use this to see what version you are running:
$ rpm -q boinc-manager

Footnote:
After finding out and ten days later, on my computer it had already amounted to 2 GB:

[.BOINC]$ ls -lc
total 2283432
-rw-rw-r--. 1 a3 a3 2338226735 Jul  6 11:53 stderrgui.txt
-rw-rw-r--. 1 a3 a3          0 Jun  6 06:52 stdoutgui.txt
[.BOINC]$ ls -lu
total 2283432
-rw-rw-r--. 1 a3 a3 2338226735 May 27 12:50 stderrgui.txt
-rw-rw-r--. 1 a3 a3          0 May 27 12:50 stdoutgui.txt