High Basepass and Render Velocities when landscape is unloaded

[Mitzhawk]

Hello!
I was optimizing the game when i found this issue.
When the camera is looking into the distance, when the landscape is unloaded the Basepass and Render Velocities are very very high.
When the landscape loads, even though there are more tris to render, the Basepass and Render Velocities go back to normal.
The map is a open world one with world partition and streaming enabled.

I have a i9 14900 and a RTX 4080 super, so even though the stats may not seem big, on lower end graphics cards the lag it creates is terrible.

I don’t really know where to look to understand the problem, GPU Profiling doesn’t give more details other than Basepass and Render Velocities (Velocity parallel).

Do you guys have any ideas?

I will leave a video and screenshot with gpu profiling here.

Debug High Basepass

[Mitzhawk]

From what i can see, it should have to do with the Render Velocities. But Render Velocitiesis are increased by motion blur. I don’t have it enabled in post processing volume, neither in project settings.

Is there any other effect that affects Render Velocities?

[Mitzhawk]

After some more tests…its seems like it is the HLOD… for some reason.
In that part of the map is mostly vegetation, and the HLOD is set to instancing.

I don’t really know why this is happening though
Any ideas?

[Mitzhawk]

Turns out…it was the landscape streaming proxy being spacially loaded creating a very high overload on the basepass and render velocities.

Render velocities has to do also with culling. It seems like it is harder for gpu to cull verry big meshes (Landscape streaming proxy)

Turning that off helped a lot. I set the whole landscape to be loaded and i tweaked the landscape LODs.

It did the trick