Low publish frequency of local_position/pose with Optical flow positioning

I used a optical flow sensor(PMW3901) and a distance sensor (TFMINI) to control my quad. The problem is that when I listen to the topic rostopic echo mavros/local_position/pose The feedback frequency is pretty slow. I think it has something to do with the px4 firmware because even without ROS, in the Mavlink Inspector in QGC, the frequency of distance sensor and flow sensor is about 10HZ. But is there a way to make the feedback frequency higher? I want to use the Z direction distance feedback to do closed-loop control. Obviously, 10 HZ is far from satisfying. Thanks.