Big rendering performance loss from 2020.3.4 to 2021.1 (Lights / ShadowCasters)

Hi everybody. I'm developing a game that uses a lot of 2D lights and shadow casters and I've just upgraded the project from version 2020.3.4 to 2021.1.0 (tried 2021.1.3 too, even 2021.2a) and quickly realized about the FPS drop, from +60 to 45 in non-development builds. I could not reproduce the exact scenario in a test project but I created a simple scene with:

• 5 sprites
• 2 sorting layers
• 53 shadow casters
• 9 lights

Unity 2020.3.4

• 140 FPS
• 3k drawcalls (3k batches)
  
• RenderPipelineManager.DoRenderLoop_Internal takes 4.67 ms
  
• ShadowCaster2D.Update called 65 times takes 0.34 ms

Unity 2021.1.0

• 100 FPS
• 5k drawcalls (5k batches)
  
• RenderPipelineManager.DoRenderLoop_Internal takes 7.55 ms
• ShadowCaster2D.Update called 65 times takes 2.12 ms

I'm quite confused, we've been told that you (Unity dev team) have been prioritizing performance tasks for the last months but I'm getting these results. Am I missing something? Is there anything in the v2021 I should tweak to get the same performance as with 2020.3.4?

I've attached the test projects.

 

Sure, I already filed this bug, sorry for not mentioning it in the original post: 1331230

 

I've been told that they have found a way to reproduce it, I guess they will now work on a solution.

https://issuetracker.unity3d.com/product/unity/issues/guid/1331230/

 

Also, is there a way to apply a single Shadow Caster on an object containing multiple sprites?

I have an object that contains head, body, arms, legs, etc.
And on each of those, I need to add Shadow Caster 2D on them.
Is there a way I can have a composite of the sprite, and apply a Shadow Caster2D on the parent object only?

 

I think the ShadowCaster2D is being calculated even when it is out of camera view.

I put a lot miles away and it is lagging.

I wrote a script to disable shadowcaster out of view and the perfomrance improved substantially (especially in scenes with lots of shadows.)

 

There's no way to do so in Unity at the moment. However, it's doable, I mean, I know the code of the URP and that's a feature that can be implemented, there's no technical impediment.

 

Still not solved, and I still don't dare to upgrade to 2021

 

@ThundThund I moved away from ShadowCaster
SmartShadow is faster... and I mean like ..... 1000x faster.
On mobiles, performance is barely impacted.

$30
https://assetstore.unity.com/packages/tools/particles-effects/smart-lighting-2d-112535

Edit: And those issues I posted above?
Smart shadow solves it using lightmap layers

 

I already solved the performance issues by optimizing how shadows are generated in Unity, and also applied some visual softening. But thanks for the reference, I will take it into account in case I find any new technical impediment.
https://forum.unity.com/threads/fea...k-and-i-wish-they-were-in-the-engine.1125893/

 

Just in case somebody is waiting for this fix, they have supposedly fixed it for URP 12, the fix is under review yet.

 

The fix has been reviewed:

"Fixed in URP 12.0.0 and 2022.1.0a6. Fixed a bug and an issue with shadow culling that were causing performance regressions"

I'm not sure about whether I will get the fix if I download the last version of the URP 12, using a version of Unity under 2022.