Having performance issues on a high spec gaming rig when in multiplayer. Smoke generally causes the problem but when even a few AI or other people on multiplayer are near each other lag spikes become frequent and game becomes difficult to play with characters aim jumping around. Even with particles at 'Standard' settings, performance takes a big dip when smoke grenades are thrown or explosions occur (from around 40FPS to about 10-15FPS).
Specs:
CPU: 2nd Generation Intel Core i7-2700k @ 4.5GHz
GPU: Palit Jetstream 2GB GDDR5 GTX680
RAM: 16GB Corsair Venegance @ 1600MHz