For performance reasons, it is important to keep in mind the distance an effect will be viewed from. Is it consistently viewed at long range or does it vary? For variable view distances, level of detail systems must be used effectively by trimming out smaller detail particles and decreasing the number of particles where appropriate.
As particles move further from the view camera, the texture applied to the particle fades between different resolution versions. These smaller textures help to increase performance and are referred to as "MIP maps." When exporting images, many image editing programs automatically generate the progressively-downsampled textures. This can work in some cases, but often one will want to hand edit each scaled texture to have greater control over the sharpness of particle effects. A specific example of this would be small embers in a fire: automatically generated details will blur and fade out at a distance, but custom painted textures can scale down to a single pixel at a large distance, keeping the fidelity of the embers.