Simulation timing in gazebo ?

edit

I have set the following condition in my world file. I want real time factor to be 1 so that both simulation and real time run at same speed. But when I launch the world file, real time factor decrease to 0.2 on gazebo screen.

<physics type='ode'>
      <max_step_size>0.001000</max_step_size>
      <real_time_factor>1.000000</real_time_factor>
      <real_time_update_rate>1000.000000</real_time_update_rate>
      <gravity>0.000000 0.000000 -9.800000</gravity>
    </physics>

Does this mean that gazebo is not able to do the calculations, because of which it is reducing the real time factor, or is there any other reason ?

PS :- Gazebo : 7.13.1 and Ubuntu : 16.04