Hi everyone,
I’m trying to track down an unusually high ShadowDepths cost in UE 5.5.4 and I’m running out of ideas.
My project is an open world using:
- Unreal Engine 5.5.4
- Cascaded Shadow Maps (NOT Virtual Shadow Maps)
- Lumen disabled
- One Movable Directional Light (Ultra Dynamic Sky)
- Nanite enabled on some of static meshes
- World Partition
I’ve already tried the following:
- Reduced Dynamic Shadow Distance to a very low value.
- Reduced the number of cascades.
- Lowered shadow resolution.
- Disabled WPO/PDO on foliage where possible.
- Verified that only one Directional Light exists.
- Tested with Far Shadow disabled.
- Optimized foliage materials.
- Tested with foliage hidden.
- Tested different shadow settings.
Despite all this, ShadowDepths consistently costs around 8-10 ms, while the rest of the frame looks fairly reasonable.
Typical GPU timings:
ShadowDepths ~8-10 ms
Nanite VisBuffer ~3-4 ms
BasePass ~2-3 ms
PrePass ~1-2 ms
What confuses me is that lowering shadow quality often just shifts GPU time into another pass instead of significantly reducing total frame time.
I also noticed that disabling landscape shadow casting removes almost all visible shadows, which suggests the landscape is heavily involved in the shadow pass, but I wouldn’t expect such a high ShadowDepths cost with the current settings.
Has anyone experienced something similar in UE 5.5?
Is there anything specific that commonly causes ShadowDepths to remain this expensive even after reducing:
- Shadow distance
- Cascade count
- Shadow resolution
- WPO/PDO
- Foliage shadow complexity
At this point I’m wondering if this is related to Landscape, World Partition, or perhaps a regression in UE 5.5’s shadow rendering.
Any ideas or profiling suggestions would be greatly appreciated.
Thanks!