Landscape splines are not culling? (performance issue)

Hi! I have 5x5km terrain landscape which has many roads made of terrain spline meshes. Performance is abysmall - I get 4FPS on my i7 CPU 1070GTX rig (basepass GPU bottleneck), even though there is nothing more in the scene. I disabled shadows and collision for segments during generation, and still. Also, even if I rotate camera away, performance hit is still in there, which makes even less sense - its like no matter what, landscape processes all the spline meshes fully (no culling). Is that true - should I submit bug report, or this is by design?

That is how my statistics window looks like:

In my case, I can see Frustum Culling eating 10ms GPU. Hmmmm… Is there really no way around, rather then making road meshes FBX meshes. Seems like right now Frustum Cull experiences overhead because it needs to process huge amount of objects (which are not combined logically, even though they are connected segments).

I also noticed that behaviour with OpenStreetMap roads generation as landscape splines. These performance problems hinder me from using them completely! :-/

Have you ran the actual GPU profiler when your frame rate tanks? You can also get a GPU snapshot by hitting control+shift+comma. From there, you need to see what’s eating up all of your frame time.

Also, have you looked into using HLODs? It sounds to me like you’re having draw call issues and HLODs are meant to help reduce draw calls by merging meshes together for LODs.