The kalarm process has high cpu consumption (≈ 50%)

The high consumption doesn't start just after starting the process, sometimes it happens after some time the process is running. The process keeps using to much cpu resources. 

Disabling active kalarm 'Active alarms' calendars stops the problem. However, when you reenable them in order to have active alarms, the alarms won't be triggered anymore.

I did test the kalarm by creating a new kalarm calendar, however with the same alarms as in the original calendar. 
I didn't test it with different alarms (to be investigated [[maybe]])

kalarm version: 2.10.10-ak
kde version: 4.13.3

Reproducible: Always

Steps to Reproduce:
1. use kalarm
2. create new alarm calendar with following entries (see attachment)

Actual Results:  
kalarm process cpu consumption ≈  50%

Expected Results:  
kalarm process cpu consumption <  20%

I did test the kalarm by creating a new kalarm calendar, however with the same alarms as in the original calendar. 
I didn't test it with different alarms (to be investigated [[maybe]])