Thanks for the comment!
Yes, the sculpting is based on TubeTrailMesh, the sculpting edits the curve. For the performance issues: my guess is that editing the curve rebuilds the entire mesh, at every frame + twice because there is actually two distinct meshes (inside and outside surfaces). After reading your message, I thought about different optimizations I could do with TubeTrailMesh, I may patch the game after the jam. You tested on Quest 2 or Quest 3?
The very next feature I intended to implement is the ability to pick-up the jar and put in on a shelf to save it, then grab a piece a clay to start a new one. I was too short on time for this.