this is in UE5.2 ↑
this is in UE5.3↓
create blank project in UE5.2 and UE5.3, create basic level, add cesium plugin, set url, set same playerstart, package shipping for windows.
this is in UE5.2 ↑
I’m afraid I don’t know what would cause that. The Cesium for Unreal code is very nearly identical between the two UE versions. All of the differences are tagged by ENGINE_VERSION_5_3_OR_HIGHER, and nothing relevant jumps out at me:
https://github.com/search?q=repo%3ACesiumGS%2Fcesium-unreal%20%20ENGINE_VERSION_5_3_OR_HIGHER&type=code
Unreal Engine itself has a lot of settings that can affect frame rate, though. And blank projects created in the two versions will not necessarily keep these settings consistent. Some things to check:
- If you create a blank project in UE 5.2, and then load it in 5.3 (versus creating a separate new project in 5.3), do you see any difference?
- What about 5.4? Does that change things at all?
- Do you see a generally lower frame rate in 5.3 even without Cesium content?
Yes, this issue was discovered after upgrading from 5.2 to 5.3, so i test it in a blank 5.3 project.
And fps is same low in 5.4 and 5.3.
I have checked .ini file in config folder, not find releation differences.
And if import by datasmith, fps is not significant differences between 5.2 and 5.3.
I just tried this out myself. I opened level 12 (Google Photorealistic 3D Tiles) of the Cesium for Unreal Samples project, and noted the frame rate in the Editor. UE 5.2 was about 75 FPS on my system, UE 5.3 was about 100 FPS. I don’t know if this experiment was 100% controlled, but I’m certainly not seeing a huge drop in UE 5.3 like you are.
So I’m not sure what what might cause what you’re seeing, but I’m struggling to think of how it could be caused by the Cesium plugin. Perhaps you could try doing some runs with the Unreal profiling tools and see if you can spot what’s taking the extra time on your system in UE 5.3?
At present, it has been found that the decrease in frame rate is due to longer GPU time, and FPS is also related to “Game” time. It seems that 5.3 has lower “Game” time. When using Google Photorealistic 3D Tiles, try compare the GPU time between 5.2 and 5.3. If possible, try using a larger model or copying the model multiple times.
I am still analyzing the specific situation further.
If 5.3 is taking longer to render on the GPU given the same models and materials, that would be something you’d have to raise with Epic. It’s probably not something we can fix on our side.
If you do see evidence that the models or materials we’re providing to Unreal are different between the UE versions, then please tell us more. I would be surprised if that were true, but sometimes surprising things happen!
One thing to watch out for, of course, is that your viewport is the same size and resolution in both versions.
On high-performance GPUs, the gap is not very significant,
On low performance GPUs, the gap is even more pronounced
I’m not sure what exactly caused it, but the test results show that Cesium in 5.3 takes more GPU time than in 5.2. However, if we directly use SMC for testing, there is no significant difference between 5.3 and 5.2. I switched to a computer with a better GPU, and the result was the same.
The following are test screenshots:
Cesium in 5.2
Cesium in 5.3
SMC in 5.2
SMC in 5.3
Here is my testing project:
TEST224083001.zip (18.4 MB)
TEST324083001.zip (18.4 MB)
NewMap1 loads SMC, NewMap loads Cesium
Thanks for the projects. Indeed this project runs much faster in Play-in-Editor mode in 5.2 than 5.3 on my system. Strangely, in the normal Editor view, the performance of the two UE versions is identical.
I did some very brief investigation, and I think the immediate reason it’s running so slow in 5.3 is because my GPU is running out of memory. Here’s the memory view in 5.2, which shows 1.2 GB used by static meshes:
In 5.3, static meshes are using over 4 times the memory!
So again, that’s Play-in-Editor mode. In normal Editor model, UE 5.2 uses the same amount of memory (1.2 GB), while 5.3 uses 2.6 GB. So 5.3 is still using far more memory than 5.2, but half as much as it uses in Play-in-Editor.
This is all very strange; I can’t explain it. But I will investigate.
I’ve opened a pull request to fix this issue:
You can try it out by following the instructions here:
On my system UE 5.2 and 5.3 show roughly requivalent frame rates and memory usage in your test project after this fix.
yes, this issue fixed in 2.9.
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