Smoke particle system using an old vfx trick of scaled and rotating single sprite texture in WebGL, plus some additive blending for extra sass :)
Color of smoke may be changed by modifying "color" attribute for smokeMaterial on line 45.
Performance improvement can be had by reducing number of particles, and/or removing "opacity" setting from smokeTex (png will supply opacity, opacity setting simply allows us to "tone it back" or make it slightly more transparent)
Low hanging fruit for visual