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Beginner: Performance Issues

Development Discussion Rendering
#1

Were currently trying to build an island with blueprinted houses. After we placed a few of them, our FPS dropped insanely low and we dont know why. Our houses are really basic, they are built out of modular parts and all unnecessary tris have been deleted. We think the count of tris can not be the issue a screenshot of our statistics is attached to this post. We already tried to use LODs with a huge reduction of tris in really short distance but we didnt had a better result. We tried to turn off dynamic shadows and similar settings, we tried to turn down some render settings.
We also thought the problem could be caused by the amount of windows we have in the scene because of stuff like alpha checks, reflections and transparency. However we placed a ton of them and it didnt cause any performance issues.
We looked up GPU stats and they showed, that “HZB” took the most ms during runtime, but we dont know what to do in order to fix our issue.

We’ve never worked with unreal before so we really just dont know what could be the problem. If you need more info in order to help us, just ask :slight_smile: Thanks is advance.

#2

From the stats you posted, it looks like you have just a lot of SM placed. For example, you have 1,980 small windows but the windows are only 4 triangles and while this is good, having over 1k of them is probally what is causing your HZB to go crazy. I would suggest that you use Merge the windows so that they are grouped togther by say floor or sides of the building. This way you will still have the modularity you want but way less meshes to process.

#3

Yes, the main issue is the number of objects, each one will impact performance even if it’s not a complex model (adds to the number of draw calls) for objects that are very simple it’s better to merge them to lower the object count. Start with things that use the same material.

#4

Try to run a packaged shipping build to see if there is any improvement, since parallel base pass rendering is disabled by default in the editor, which affects the performance of rendering large number of objects.

Also the “HZB” part is actually not accurate because it shows CPU bound time. This issue has been fixed: Unreal Engine Issues and Bug Tracker (UE-33448) but still need a while to get into the release.