Increase in Engine Stats for large amounts of Hierarchical Instanced Static Mesh Components

Increase in Engine Stats for large amounts of Hierarchical Instanced Static Mesh Components

User Description:

We are having performance drops of almost 5ms in 4.15 when using "Hierarchical Instanced Static Mesh".

There is no change in the lighting. Just did regular upgraded copy of the project. There are about 50,000 hierarchical instanced static meshes. Here are link to test project for both 4.14 and 4.15

1. Unzip the attached project
2. Right-click on the .uproject > "Generate Visual Studio project files"
3. Once the project is open > PIE
4. Click to gain focus but try not to move the camera view
5. Press the ~ key and enter the console command "stat engine"
6. Screenshot the stats
7. Close the project > Open 4.15 or 4.16 > Convert a copy of the 4.14 project
8. Once opened > PIE
9. Repeat steps 4-6

Results: The overall engine stats will be higher in 4.15+, specifically the FrameTime and FrameScyncTime will be much higher.

Expected: For an unchanged project scene to get similar or better performance in a later engine version.

Performance drop with Hierarchical Instanced Static Mesh in 4.15