IsaacSim 6.0.0 low FPS while IsaacSim 5.1.0 high FPS on certain scene

[chenhzhu]

Description

The IsaacSim 6.0.0 has very low FPS on the props gallery scene.

Many of my custom props in the scene don't have collision enabled while some NVIDIA props have.
But this scene has very high FPS in IsaacSim 5.1.0 version. And the scene is also built using IsaacSim 5.1.0.

I wonder what makes FPS decreased so much in IsaacSim 6.0.0. My other scene also have FPS decrement but not so much like this.

Gallery scene link:
https://drive.google.com/file/d/16oz1U3reklU5RVGT63cEB2if7X6ErYmL/view?usp=sharing

Isaac Sim version

6.0.0

Operating System (OS)

Ubuntu 24.04

GPU Name

RTX 4090

GPU Driver and CUDA versions

575.57.08

Logs

No response

Additional information

No response

[vick-yu]

Hi @chenhzhu — thanks for the report. We ran comparative benchmarks between 5.1 and 6.0 on an RTX 6000 Ada (same codebase, same hardware) and can confirm there is a measurable performance difference.

The degree of regression varies by workload — render-heavy scenes are affected more than physics-only workloads. Your props gallery scene with many custom meshes likely falls in the render-bound category, which would explain the larger FPS
drop you're seeing.

We're investigating this internally. A couple of things that would help us narrow down your specific case:

1. Scene file access — the Google Drive link currently requires requesting permission. Could you update it to "Anyone with the link"?
2. FPS numbers — what approximate FPS are you getting on each version? The screenshots are hard to read at this resolution.
3. Render mode — are both running the same renderer (RaytracedLighting vs PathTracing)?

[chenhzhu]

Hi @chenhzhu — thanks for the report. We ran comparative benchmarks between 5.1 and 6.0 on an RTX 6000 Ada (same codebase, same hardware) and can confirm there is a measurable performance difference.

The degree of regression varies by workload — render-heavy scenes are affected more than physics-only workloads. Your props gallery scene with many custom meshes likely falls in the render-bound category, which would explain the larger FPS drop you're seeing.

We're investigating this internally. A couple of things that would help us narrow down your specific case:

1. Scene file access — the Google Drive link currently requires requesting permission. Could you update it to "Anyone with the link"?

2. FPS numbers — what approximate FPS are you getting on each version? The screenshots are hard to read at this resolution.

3. Render mode — are both running the same renderer (RaytracedLighting vs PathTracing)?

Thank you @vick-yu for your help.

1. Just updated. I guess the skybox I used makes the FPS very low in IsaacSim 6.0 which I don't know why..
2. In the screenshot, the IsaacSim 6.0 FPS on the right top shows 16-17; the IsaacSim 5.1.0 shows 112-118. When moving the viewport camera, IsaacSim 6.0 can feel obvious laggy while IsaacSim 5.1.0 is pretty smooth.
3. For render mode, I used the default mode after I run isaacsim in terminal, for IsaacSim5.1.0 I believe it's Raytracing (Realtime); and for IsaacSim 6.0 it's Realtime2.0 (I guess it's also raytracing ?) so both are the same renderer.
   (↑ IsaacSim 6.0.0, ↓ IsaacSim 5.1.0)

[vick-yu]

Hi @chenhzhu,

Thanks for sharing the scene file -- it helped us pinpoint the issue.

This is not a general performance regression in Isaac Sim 6.0. After profiling your scene, we found that several Present thread-related settings are enabled in your USD asset that are off by default in Isaac Sim. These settings add extra synchronization points between the render and present threads, which in 6.0 can cause the threads to get out of sync and enter a low-performance loop.

In 5.1, these same settings happened to not cause a visible slowdown because the thread scheduling was different, but the underlying misconfiguration was still present.

To fix this, check your scene's settings layer for any Present thread overrides and disable them. Specifically, look for settings under:

• /app/renderer/presentThread/...
• Any synchronization-related render settings that differ from the defaults

After removing these overrides, opening the same scene in 6.0 should yield performance in line with (or better than) 5.1. If you're unsure which specific settings are causing the issue, you can try opening the scene in a text editor and searching for presentThread in the USD customLayerData or session layer. Let us know if you need help identifying them.

[chenhzhu]

Thank you @vick-yu ,
I didn't find where to modify the renderer setting in the IsaacSim GUI... So in IsaacSim I saved the .usd scene as .usda and opened it in text editor. When search in the .usda for presentThread, it can't find any.

Could you be more detail on how to find the presentThread in IsaacSim ? Or how I could identify the async render related setting in the .usad file.. Thx 😵‍💫

Converted to .usda using IsaacSim 6.0.0: https://drive.google.com/drive/folders/1_Eo-y3oHhto_K_wEbtxWfeZmmx76Y61c?usp=sharing

[ssulkunte-nv]

Hi @chenhzhu, you can find the relevant settings under the Developer section of the Preferences pane. All settings related to Present thread can be disabled and there was also a 60 UI FPS limit imposed that can be changed to the default of 120 to get equivalent performance to 5.1. This should give a much smoother UI experience. You may need to toggle Play/Stop or save the stage with the changed settings and reopen to see the increased performance. Local testing of your scene improved performance from ~16 FPS to 120 FPS on 6.0 with the setting changes.

[chenhzhu]

Thanks @ssulkunte-nv ,
Yeah I found the Present Thread settings. Somehow the Google drive version of the .usd toggled on those 3 Present Thread settings. For my local .usd it's by default off (which is strange I barely did nothing but make zip file)...

For both local .usd and Google drive .usd, after toggle off those 3 option, when dragging the viewport camera, the FPS still around 18 for both Play or Stop ...
(↑ local usd, ↓ google drive usd)

The no present thread usd for both google drive version and local version:
https://drive.google.com/drive/folders/1iOwo5llwcWsSAFywHMIK9a1L2DcfZnDn?usp=sharing