Multiple obi solvers

[lufydad]

Thanks ! It works a lot better with only one ObiFixedUpdater .

For the "death spiral", I'm aware of it and I currently have some algorithm that dynamically choose a fixedDeltaTime between 1/30 and 1/120 to be more consistent with the simulation time.

However, I still have 2 problems with performance :

1. When my 4 gameobjects with ropes are instantiate, I have a performance hit, due to obi fixed update (see capture https://imgur.com/a/0V04YNb). Have you an idea of where it comes from ? And how could I reduce it ?
   
2. Globally with 12 ropes of a few meters (approximately 1500 particles in total), 2 iterations for bending and distance, The performances are "only" near 30 fps. Is it normal ? (Unity 2021.2.4, CPU : AMD Ryzen 7 4800h, GPU : Nvidia RTX 2060, RAM : 8 GO)