Gazebo : Sim time results very slow compared with Real Life

Hello, I’m a newbie on Gazebo. I made already my quadruped robot, but I would like to simulate it with Gazebo.
I created a simple ball with a box. ball with collision, and box without collision.

ball : radius = 0.014, mass = 0.013, friction : mu = 0.01, mu2 = 0.01
box : size = 0.04, mass = 0.022

When the ball falls over the plane, (with rotation) the ball rolls due the mass of the box. That works, but unfortunately very slowly compared with the real life.

Sim time : 30 seconds to do the same in Real life at only 1 second.

Perhaps I’m missing something ? The mass units is Kg right ?
My objects are very small I can’t see the problem.

Thank you