Even though the springs connecting the particles are infinetely strong, that doesn't solve the problem. When you solve multiple constraints, the kinetic energy still accumulates to the object, because when you correct one spring in a multispring body, it will make some other constraint to go out of limits. This is why you have to use more iterations. The more complex constraints, the more iterations you need for the constraints to be satisfied correctly globally.
In hitman it certainly hasn't been solved. They use as many as 10 iterations for the bodies. And in Hitmans case it really is not such a problem anyway, because there's no body to body collisions, only body to static scenery, where the kinetic energy doesn't become a problem.
You start to see problems, when you stack lot's of different weight objects on top of each other with high gravity. With little iterations they interpentrate a little and when you suddenly take of gravity they all go flying in the air. That's because the kinetic energy is released, which is formed by the constraints not been solved globally. But 4 iterations is enough in most cases to solve very complex scenario if the objects are moving at reasonable speeds.
In hitman it certainly hasn't been solved. They use as many as 10 iterations for the bodies. And in Hitmans case it really is not such a problem anyway, because there's no body to body collisions, only body to static scenery, where the kinetic energy doesn't become a problem.
You start to see problems, when you stack lot's of different weight objects on top of each other with high gravity. With little iterations they interpentrate a little and when you suddenly take of gravity they all go flying in the air. That's because the kinetic energy is released, which is formed by the constraints not been solved globally. But 4 iterations is enough in most cases to solve very complex scenario if the objects are moving at reasonable speeds.