Hi,
I updated my Windows VR application from UE5.3 to UE5.5, and noticed that performance dropped significantly in maps with a large number of Static Meshes.
Using Unreal Insight, I found that the Base Pass time increased by about 10x compared to UE5.3.
To investigate further, I also tested with the VR Template. In UE5.3, most materials appeared green in the Shader Complexity view, but in UE5.5 they are mostly red.
In particular, the Base Pass Shader Instructions count has increased.
For example, with the included material M_GridRotation:
• UE5.3: 263
• UE5.5: 351
• UE5.6: 352
I confirmed that the same issue persists in UE5.6, so the problem remains in the latest version.
I tried adjusting DefaultEngine.ini settings, but these only reduced the count slightly (about 10 instructions at most):
• Disabled Ray Tracing
• Disabled Velocity pass
• Disabled Skin Cache shader compilation
• Disabled Separate Translucency
• Disabled Virtual Shadow Maps (using CSM instead)
Questions
-
What changes in UE5.5+ cause the Base Pass Shader Instructions to increase compared to UE5.3?
• Is this due to a change in how instructions are counted, or are shaders actually heavier in 5.5/5.6? -
Are there any recommended settings or workflows to bring UE5.5/5.6 performance closer to UE5.3, especially for VR (Forward Shading + MSAA)?
-
Is this a known issue with the VR Template / Forward Shading pipeline in 5.5/5.6, and are there any planned fixes?
Environment & Reproduction
• Platform: Windows (PC VR)
• Template: VR Template (new project created in UE5.3 / UE5.5 / UE5.6)
• Steps: Open the template in each version, view Shader Complexity and Base Pass Shader Instructions for materials
• Result: Instruction count is consistently higher in 5.5/5.6 (e.g., M_GridRotation = 263 → 351 → 352)
My goal is to achieve UE5.3-level performance in UE5.5/5.6.
Any insights or advice from Epic staff or other developers would be greatly appreciated!
Thanks in advance.