Performance drop with Hierarchical Instanced Static Mesh in 4.15

We are having performance drops of almost 5ms in 4.15 when using “Hierarchical Instanced Static Mesh”. I am attaching screenshots of both 4.14 and 4.15 version.
Please let me know if you need more information regarding this.


Hi ,

I attempted to reproduce this using about 10,000 hierarchical instanced static meshes but the FrameTime and other stats actually got faster for me after upgrading to 4.15.

4.14 - Avg. 8.47 ms | Max. 12.91 ms

4.15 - Avg. 8.34 ms | Max. 10.13 ms

Looking at your screenshots, there also looks to be a difference with the lighting from screenshot 1 to 2. Did you change anything after upgrading to 4.15?

How many instanced static meshes are you using in your scene? Would you be willing to upload a test project that has the issue?

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

Here are some screenshots also of test project comparing both 4.14 and 4.15 version and still about 6ms difference.

Thanks for help and let me know if you need more info.

Hi TJ,
Were you able to download and test the CrowdTest project? Please let me know if you need anything else.


Hi ,

Sorry for the delay. I downloaded your test project (thanks for uploading it BTW) and I was able to reproduce what you are seeing. I’ve created JIRA UE-44134 and our devs will be investigating further.

I’m unsure of what could be the cause. There was some fixes/changes to Hierarchical Instanced Static Mesh Components and materials in 4.15. It could be any number of things. Follow that link to monitor the status of the report.



Thanks for helping out.

4.16 the same issue