Slow sim rate Ignition Gazebo and DART

Hi all,

I’m using Ignition Gazebo with DART. I have a use case in which multiple objects are in constant collision with each other, e.g. a stack of boxes. The DART physics engine seems to struggle with this case, slowing down the sim rate (RTF) to 25% on my machine. In contrast, when using the Bullet physics engine the simulation seems to run smoothly at a ~97% rate. Check links to images below:

DART
Bullet

What’s interesting is that when using DART physics engine but selecting dart::collision::BulletCollisionDetector as the collision detector, the sim still runs slow at a 25% rate. Can anyone provide an explanation, or give some intuition regarding this phenomenon? I’m not extremely familiar with physics engines so any clues will be useful.