Add a ragdoll attachment to the rope's end

[josemendez]

I tried that. If I disable only the solver, the rope remain in that state, but the body in the end falling down.

Ofc you need to disable any objects attached to the rope too. If you just disable the solver, all objects in there won't have any ropes supporting them so will just fall to the ground. Rigidbody objects are not simulated by Obi so disabling the solver won't stop their simulation.

After I enable it again... The body will be in the end, but also a big force apply on the rope, so the rope suddenly moving with big speed

Yep, that's the expected behavior if you disable the solver but not the attached objects. Once you re-enable the rope simulation, any stuff attached to the rope will spring back to it.

Also if I disable simulate when invisible is the same behaviour like I mentioned before. Big force apply to the body in the end

Other objects in the scene (rigidbodies) are not handled by Obi, so when the solver stops simulating the rope, rigidbodies will still be simulated by Unity. You need to deactivate them too.

Also the fps going down to 1-10 fps with the solution you mentioned. With my solution only enabled/disabled the gameobject the fps is 20-30 fps.

By disabling the entire game object hierarchy will lose any temporary state (cuts, length changes) in the rope. Disable the solver component only, then disable any other objects (rigidbodies) that interact with the simulation. This will result in *zero* work being done.