Watch the Mist. INTENSITY: How many mist particles there are. The more intensity the more realistic. VISIBILITY: How easy the mist is to see. I suggest the visibility to be 1, or if you have low intensity 3. WIND: How fast the mist moves. I suggest 35.
LAG IS POSSIBLE. I made everything. The more intensity you add the more the mist has to load. The more visibility, the less realistic. The less visibility, and the more intensity, the more realistic.
