How to set publishing rate for uORB publisher

I implemented a module publishing to actuator_controls_0 topic, which is supposed to run at a rate of 250Hz. When I start my module the rate changes to something between 800kHz and 1.2MHz. At least that is what happens in SITL. On the pixhawk PX4 just crashes instantly. Why is this happening and how can I make my module publish at the normal 250Hz rate?