Timer from QML seems to be not useable

[Snoopy]

Hello,
I want to use the QML timer. But it works really catastrophic. If I don't do anything at the same time, only watching, the Timer works correctly. But if I moving the mouse a little bit or scrolling a listview the Timer doesn't work correctly. Then the onTriggeredEvent will be fired only after 180ms or more. Sometimes only after 200 ms.
It's a embedded system on which the application runs with Linux Kernel OS and CPU is AM4378 from Texas Instruments

I checked it on this way:

    Timer {
        id:timer
           interval: 100;
           running: false;
           property double timeStart: 0
           property double diff: 0

           onTriggered:
           {
               diff = new Date().getTime() - timeStart
               console.log(diff)
               timeStart = new Date().getTime();#
              running = true
           }