Good thing you made. The performance issue is due to network ownership.
Network ownership is where the server turns physics calculations over to a client to ease the burden of calculating physics. To prevent this just use SetNetworkOwner(nil) this will set the ownership of the rag doll to the server and make sure no lag happens on the client.
aint gon lie gang i dropped the project 2 years ago but i think the issue was the model itself because im using a blocky skinned mesh ragdoll and its lag free
(to be fair its only the arms and legs that are skinned meshes so i cant be entirely sure)