Users over at reddit got me on the right track: http://redd.it/24kogy
As suggested there QTimer
works fine. In the class of your widget you could apply it like this:
timer = QTimer(self)
timer.setInterval(20) # interval in ms
self.connect(timer, SIGNAL("timeout()"), self.update)
timer.start()
Relevant imports are
from PySide.QtCore import QTimer, SIGNAL