When Gravel or sand is falling on cobweb it is falling very slowly through the cobweb and then dropping, instead of dropping right away.

What I expected to happen was...:
When gravel and sand was falling onto cobweb, I expected it to drop right away, like it does when it is falling on a torch.

What actually happened was...:
The sand or gravel was falling very slowly through the cobweb, and then dropping when all the way through. Plus if there is more sand or gravel block on top of each other they will merge into each other while falling through the cobweb, in a way that looks very glitchy.

Steps to Reproduce:
1. Place a cobweb.
2. Place several gravel or sand blocks on top of the cobweb.
3. Destroy the bottom sand or gravel, so the rest will fall on the cobweb.
4. Observe.