EditableMeshes cause extreme FPS drop on PC

Bug Reports Engine Bugs
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1

I use EditableMeshes in my game and PC players experience massive FPS drops only when changing the UV and Position of the EditableMesh. I had an update about 3 days ago, and there were no problems. However, randomly, client FPS started dropping (and I published 0 changes). Also, I am 100% sure that it’s a result of changing the UV and Position of the EditableMeshes because when I commented out the 2 lines of code that changed them, the FPS was perfect. There are 7 EditableMeshes having their Position and UV changed on a RunService.PreRender connection.

Important info:

  • Only happens in Roblox player, not Roblox Studio
  • Only happens on PC, not on mobile (haven’t tested console)
  • Happened out of the blue, I made 0 changes, and it just started randomly happening.
  • I even tried reverting to the first time I published the update, and the issue was still there, which is why I’m so positive this must be something on Roblox’s end

Here is a video comparison of the FPS in Roblox Studio vs. Roblox Player:


Expected behavior

There would be no FPS drops in-game while the 7 EditableMeshes are having their UVs and Positions changed, just like how it was when I had initially released this update and like how it is in Roblox Studio.

A private message is associated with this bug report

6 Likes
2

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The last modified time here is very accurate to when the issue started happening (EST; August 27th, 2025 at 6:43 PM). So, another reason why I think this is due to Roblox

1 Like
4

Bump, i play the same game, i experience the same issue too, it didnt happen before, all i noticed was that it was performance heavy, but nowhere near the frame drops it is now.


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5

I think this is the same bug:

1 Like
6

Thanks for the repro file, it was very helpful.

I was able to repro the slowdown on 688.0 on windows, but I’m unable to repro it on 688.1 which rolled out on the 29th. Are you still seeing this slowdown?

7

Agreed, it does look like the same issue as Low FPS due to EditableMesh "transcodeVerticesAndCalculateBounds" taking significantly longer than usual (40-70ms frame time)

Since that other bug is resolved, I’m going to assume that this one is too, but please let me know if you’re still seeing this @Zalekoth, or if it happens again.

Thanks!

8

I’m still getting this issue, has completely tanked performance on my game as it uses editablemesh to animate grass (it doesn’t mess with UVs, just calls SetPosition on vertices)

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1 Like
9

I am having this issue too on my own project and trying out other games that use editable meshes like VOYAGERS

10

Hey, thanks for getting back to me.

I just checked my game, and I do still have this issue.

11

Great, thanks all for the replies. Could you double check what version of the client you’re seeing these on?

Thanks!

12

I’m seeing it with these version numbers:
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1 Like
13

This version:

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1 Like
14

Hey Ya’ll if anyone else is coming to this post for this issue. L3Norm announced on the other post that

“An update on this - it appears to be dependent on the exact memory layout of compiled code in some windows builds, which is why it happens for some builds but doesn’t happen on other builds.
There is a fix in, which should be in next week’s release.”

1 Like
15

It looks like the fix for this is in 691, which should be available now. I’m no longer able to repro the slowdown, but let me know if you see it again on 691 or later.

Thanks!

1 Like