Particle Effects Too Expensive
An effect eats the frame time
Also known as: VFX performance · Particle overdraw · Niagara expensive · Particles slow game · Particle fill rate · Optimize particles
Quick answer
Particle effects are usually expensive because of overdraw: many large, translucent sprites stacked on top of each other, each shaded across a big part of the screen. Use fewer and smaller particles, trim the sprite shape tightly so transparent pixels are not shaded, use simpler materials, and consider Masked or dithered opacity where it looks acceptable. Check the shader complexity and overdraw view modes to find the worst effect.
How to fix it
Profile on the target hardware, since mobile and VR are far more sensitive to fill rate. Reduce the screen coverage of effects at close range, fade large particles near the camera, use LODs for effects and cull them at distance. In Niagara, use cutout geometry on sprite renderers and GPU simulation for large counts. A few well-made flipbook sprites usually beat many simple ones.
