Tiny lagspikes when applying radius damage to a destructible

These lagspikes came with 4.8. Everytime I apply radius damage to a destructible that has already been destroyed a lot I get a tiny lagspike. Is this a known issue, and if so are there any workarounds?

Maybe worth noting; the cell site count of the destructible mesh is 1000. (However in UE 4.7 I had the cell site count on 2000 with no lag at all.)

Hi EnricoUniverse -

Thank you for your report. We have assigned this issue to a member of our support staff, and they will begin investigation as soon as possible. If we are unable to reproduce the issue, or we need additional information, our staff member will comment here with additional questions. Otherwise, we will post an ‘Answer’ once we have logged the issue in our bug database or we have a solution for it.

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Thank you -

Eric Ketchum

Hi Enrico,

I’m afraid I’m not seeing the same issues you have reported.

I’ve setup a simple test scene with a cube mesh that has 1000 fractures. I’ve used the level BP to apply radial damage to my destructible. I’ve set the Base Damage and Damage Radius to 50.

I’ve set this all up to be on key press. I start my level and press the key to apply the damage to fracture my mesh.

In 4.8 I’ve got the same setup when compared to 4.7. I’m actually seeing slightly better performance in 4.8 than 4.7 and I’m not experiencing any lag that has been described. This can change from system to system since DMs are handled on the CPU and not the GPU. Also, using DMs with excessive amounts of fractures is not recommended. Unless you change the hard coded values, there can only be 2000 fracture chunks in a scene at a given time.

If you have a sample project you want to upload I can have a look as time permits, but I’m not seeing a regression in performance from my test setup.

Thank you!


Thanks for the response.
Is there a way that I can send the project to you only? Like via e-mail?

You can send me a link the project via a private message on the forums at this link: https://forums.unrealengine.com/private.php?do=newpm&u=4894

If you can, send me the 4.7 project. I can then make a copy of it in 4.8 as a test much more easily for testing.

Thank you!


I have send you a private message.

Hi Enrico,

I had a quick look at the project and I’m not seeing any lag when I’m shooting the DM.

If you’re noticing any type of lag or bottlenecks in your FPS you will probably want to start profiling to see where these types of hitches are happening.

I highly recommend this Support Stream that we did a little while back: Rendering Best Practices | Live Training | Unreal Engine - YouTube

You can also read the documentation here that is referenced in the video:

Since DM’s are handled on the CPU you’ll want to profile there more than the GPU.

In my initial test I had setup a DM in 4.7 and the same in 4.8 by applying damage with a DM that used 1000 fractures. There is always an initial hit to the FPS because when the DM fractures you now have X number of physics bodies in your scene that need to be accounted for. Increasing the number of fractures will cause this along with the system specs of the machine you’re using.