Bombsite B in Overpass is unplayable

[wildcard-f8]

Your system information

• System information from steam (Steam -> Help -> System Information) in a gist:

https://gist.github.com/wildcard-f8/6bcc20bb40cb0d1d960621cd6ec755ca

• Have you checked for system updates?: [Yes/No]

Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large pastes as a Github Gist.

When any player walks on water in bombsite B causes everyone's FPS to drop. Even in the lowest setting. When all players are in B and throwing smoke and walking in water the FPS goes from 140 to 1. Over a long game, especially in overtime, the FPS even when no one is walking in water causes the average FPS to drop every round.

Steps for reproducing this issue:

1. Play Overpass
2. Go to bombsite B
3. ?