pointcloud_to_laserscan pub rate very slow

edit

Here is the launch file of my pointcloud to laserscan publisher;

<launch>

<!-- run pointcloud_to_laserscan node -->
<node pkg="pointcloud_to_laserscan" type="pointcloud_to_laserscan_node" name="pointcloud_to_laserscan">

    <remap from="cloud_in" to="/camera/depth/points"/>
    <remap from="scan" to="scan_filtered"/>
    <rosparam>
        target_frame: camera_link # Leave disabled to output scan in pointcloud frame
        transform_tolerance: 0.01
        min_height: 0.0
        max_height: 1.0

        angle_min: -1.5708 # -M_PI/2
        angle_max: 1.5708 # M_PI/2
        angle_increment: 0.0087 # M_PI/360.0
        scan_time: 1
        range_min: 0.45
        range_max: 15.0
        use_inf: true
        inf_epsilon: 1.0

        # Concurrency level, affects number of pointclouds queued for processing and number of threads used
        # 0 : Detect number of cores
        # 1 : Single threaded
        # 2->inf : Parallelism level
        concurrency_level: 1
    </rosparam>

</node>

</launch>

But as i saw the output publish rate i.e scan_filtered is very very slow around 0.3 average rate shown by the rostopic hz. Which parameters should i change to increase the pub rate of the scan_filtered? Here i have transformed the depth_frame link to camera_frame for correct transformation of laserscan.