I have two meshes, both created in blender with the GIS plugin that I'm running in Gazebo 9.19.0 ROS Melodic. One is very large (800m x 200m) with 600,000 vertices and a 50cm resolution tif (259MB dae with 7MB tif) and it runs with a Real Time Factor (RTF) of 1.0 with no issues on my i9, RTX 2080ti, 64GB ram computer. The other is much smaller (100m x 150m) and I decimated it to 12,000 vertices and replaced the texture with a single color (4MB dae with 455KB tif). The smaller one will only run with a RTF of 0.01 on the same machine.

Both are using the same world file, with different names for the dae. Both meshes are triangulated. The only difference is the faster mesh was created using a DSM from photogrammetry and the other was created using a DSM from LiDAR. The meshes look very similar, especially once I smoothed and decimated the LiDAR mesh. I've tried everything I can think of to make the smaller mesh work, does anyone have any suggestions that I might be missing?

Attached are my world file and two screenshots of the wireframes in Gazebo.

C:\fakepath\racetrack_part.world C:\fakepath\Screenshot from 2021-08-04 10-08-12.png C:\fakepath\Screenshot from 2021-08-04 10-12-23.png