It could be a number of things, the mesh being too small, the paint value being too low or high (maybe) in certain areas. The simplest solution would be to take a look at the free examples from fab for cloth. You may be able to just copy the cloth directly from there.
You can’t expect a simulation to collide with and work against a planar collision for instance. Particularly given the highly inadequate chaos solver that they forced into the engine…
so try using a cube as a sropping element. Of at least 1m i’d say. And pefromance/math is still going to be 100% fps dependent.