You might probably want to reduce the number of cloth vertices for the leaf - the more detalized the cloth is, the more "silk-like" it behaves.
Also, I believe, there should be parameters like bending resistance to tweak.
I try to reduce the number of leaf vertices until it just includes 8-13 vertices I can get a good effect. but leaf shape will become monotonous. If I want to implement some deformation to leaf, it will be troublesome.