Layered Clothing - updateInvalidatedFastClusters triggered by rapid "Enabled" state toggle of LinearVelocity constraint

[SigmaTech]

Uniquely designed character controllers in my latest game have uncovered strange triggers to updateInvalidatedFastClusters seemingly related to physics constraints. Colleagues of mine have pointed out previously resolved issues related to updateInvalidatedFastClusters in other scenarios:

updateInvalidatedFastClusters/updateEntity triggers on character descendant part property changes, causing spikes

updateInvalidatedFastClusters called every frame for animations played inside viewport frames

My particular issue focuses on updateInvalidatedFastClusters as it relates to physics constraints. More specifically, LinearVelocity.
In addition, colleagues have also helped identify triggers caused by rapidly equipping and unequipping tools:

All of the stress tests of updateInvalidatedFastClusters mentioned above can be reproduced and observed in this file I have spent a whole day distilling and isolating from a larger tech stack: LC_updateInvalidatedFastClusters.rbxl (64.7 KB)

Please open the updateInvalidatedFastClusters script under StarterCharacterScripts and read the top of the file for more context.

To simplify and save time observing microprofiler, I recommend the following:

• Switch microprofiler Mode to “Timers” instead of “Detailed”.
• Pan to the “Render” group right under “Network” and “Heartbeat”
• In the “Render” group, you should see a few bars fluxuating:
  • Prepare (~13ms max time¹)
  • UpdatePrepare (~13ms max time¹)
  • updateInvalidatedFastClusters (~13ms max time¹)
    …
  • upload (~8ms max time¹)
  • updateEntity (~13ms max time¹)
  • updateGeometry (~13ms max time¹)
  • finalize (~12ms max time¹)
• Left click any of these to observe the graph in the bottom right corner

¹ System Information

• Windows 11
• Intel Core i7 9700k, 32 GB
• NVIDIA RTX 2080

Thank you!

@SigmaTechRBLX on X
Sawhorse Interactive - [F] Software Engineer
Supersocial - [F] Software Engineer
Voldex - [F] Gameplay Programmer
Red Manta - [F] Gameplay Programmer

[V4_Ap3Dud3]

Hello and thank you for reaching out and reporting the issue. This is currently being worked on and in final stages of fixing/releasing. Please stay tuned. We are currently working on verifying and fixing edge cases.

Thank you for your patience!