Alternative Means of Creating Effects
Sometimes, an effect you are tasked with creating might not be a particle effect at all. There are many cases in which it might make more sense to create your effect using a mesh instead of a particle system. For instance, there might be several cases throughout your project where you have large columns of smoke and fire off in the distance. To render these columns using particles, we would run into several issues.
The Game Thread cost of updating the particle systems associated with keeping the emitters around ticking.
The GPU cost of rendering large groups of particles, drawing over each other to create a volume.
This can also be the case for instances where you might need to create flowing water or any dense volume which might require large amounts of particles. The cost associated with placing a Static Mesh is significantly lower than the cost of placing and updating a particle system. In some cases, mixing a Static Mesh with particle systems may yield the most dynamic result. Experiment and find the solution which fulfills your scenario the best.
An effective Effects Artist finds ways of using multiple systems within UE4 to balance visuals with performance.