HDRP Performance Regression After Upgrading from Unity 6.2 to 6.3

[unity_27NFUoGCKItEVA]

Hi,

After upgrading our project from Unity 6.2 to Unity 6.3 (HDRP), we’re observing a noticeable performance regression in the exact same scene with no content or settings changes other than the engine upgrade.

Metrics (same scene, same hardware, same settings):

Total frame time:
6.2 → ~6.7 ms
6.3 → ~7.1 ms
Render Thread:
6.2 → ~3.3 ms
6.3 → ~6.0 ms

These are much worse numbers in 6.3. Please see the attached screenshots for detailed profiler captures.

6.2

6.3

Pipeline: HDRP
Scene content and quality settings: unchanged between versions
Only action performed: engine upgrade from 6.2 to 6.3

Can you clarify what has changed in Unity 6.3/HDRP that could explain the higher render-thread time and overall frame-time increase? Are there known regressions, new defaults, or additional passes/features enabled by default in 6.3 that would account for this?

Any guidance on configuration changes, toggles, or known issues to investigate would be appreciated.

Thanks in Advice,
Jakub

[bstooler]

Is this the same in builds ?

I am considering starting with Unity 6.3, though this may affect it a lot

[benjr34]

Have you figured the reason out yet?

[Squashi]

We have a similar issue using URP, but have not conducted any specific tests

[DevDunk]

If you have a reproducible change, please file a bug report with both projects attached. That landed multiple fixes for me ok the VR side

[hrclogic]

Facing same issue in built in RP as well

Performance regression in Unity 6.3 BiRP

Hello After updating my Unity project from 6.0.58 to 6.3 I am facing performance regression in the same scene and no code changes. After doing a CPU capture in PIX I found Gfx.WaitForGfxCommandsFromMainThread has jumped to 1.5ms from 0.2ms Unity 6.3.1: [image] I am using GPU driven rendering in built in render pipeline and I am calling Graphics.RenderPrimitivesIndexedIndirect for all the static geos in Update(). Has anything changed in Unity 6.3 that I need to change my code or is this a re…

[sartubakia]

Same in our project, fps drop from 90 to 55

[Liam2349]

You should attach the profiler to both projects, then you can find out what’s different.

[sartubakia]

That should be nothing different, i am just return to 2.15 from 3 and FPS is now fine again.
This is not major update, just rework of render graph in 6.3 as i know.
Just look like a bug, nothing new

[ryanspark450]

Facing the same issue.

[fendercodes]

I’m also seeing a noticeable drop in performance. Any idea what happened?

[mgeorgedeveloper]

Can confirm - huge drop in play-mode performance after going from Unity 6.1 to 6.3… at least in the Editor. Nearly unplayable on older PCs.

Maybe this relates to render graph “upgrades” or changes? I’m just guessing, but it seems something went wrong.

[DevDunk]

Then file a bug report so it can be fixed

[Qleenie]

Saw same issue in URP project, big performance drop (GPU time) after updating form Unity 6 to 6.3. Cannot do a bug report due to size of project and legal reasons, though. Tested in build, of course.

[Neonage]

Try switching graphics API from DX12 to Vulkan, might get better. I also feel constant and frequent spikes/lags in any project, but it seems like an Editor only issue.

[DevDunk]

Usually switching to dx11 is the best for windows

[Qleenie]

We saw similar performance regression going from 6000.0.63f1 to 6000.0.71f1… We are using DX11. Also after updating, shader compile errors starting to appear related to UnityTexture3D, so there was definitely a deeper change somewhere. BTW error happens on a Unity owned package (hair package). This is not good to have this deep of changes on minor LTS versions without any warning (at least i did not find any, going carefully through all release notes of 6000.0.64 to 6000.0.71).

Performance regressions we see are all GPU related. The regression on Unity 6 LTS line only affects the hair package, but updating to 6.3 affects most of our compute shader (not render graph, though).

Edit: Made a separate thread for the Unity 6 LTS related issue:

Updating from 6000.0.63f1 to 6000.0.71f1: Big performance regressions and shader error related to UnityTexture3D

As the title says, we observed two things after updating Unity from 6000.0.63f1 to 6000.0.71f1 in our production project (DX11 / URP): shader code using UnityTexture3D did not compile anymore (in this case from Unity’s hair package) we observed a big performance hit (GPU time) on same package after fixing the compile issue (by initializing “hdrDecode” zero values). Whatever has been fixed in one of the updates between 6000.0.64 and 6000.0.71 completely destroyed GPU performance in our projec…

[Qleenie]

So the regression in Unity 6 was due to a Prefab being completely changed by the Unity update, with setting some properties of components to different (default?) values. Just did a compare in Git, and one prefab is basically completely restructured after the update. That’s a big mess… but unrelated to any performance regressions of Unity 6.3.

[Qleenie]

That being said, we still have the issue of bigger performance regression in 6.3 and cannot update due to this reason.

[Qleenie]

And to back it up with some numbers (URP, DX11, measured in build with RTX 3080):

GPU performance is 0.1-0.2ms worse with 6.3 compared to Unity 6; measured in build, with most compute based features in our game turned off. This seems to be the “standard” delta, which is quite big already. Biggest issue is with Unity hair package, here we see a drop of 1-3ms GPU performance on more complex hair styles!

Not sure how to find out where the actual delta origins from without having same project installed twice on same machine with different Unity versions (which is quite a hassle for us due to project size).

But seeing the number of reports in this thread across all render pipelines it seems there is something wrong with Unity 6.3.

Maybe someone from Unity team can step in and give hints what to try or how to report this issue.