Unity C# instantiates a child object at run time based on frequency or usage. This improves performance, as it can be used to instantiates particle effects only when they are needed, also reduced particle emissions when frame rate drops below a specified amount.

InstanceAdd.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
namespace ProjectKing {

 /**
 //Add this script to a gameobject that you would like to instantiate a particle effect object 
 //Also optimizes particle emmisions based on frame rate drop
 //
 **/

 public class InstanceAdd: MonoBehaviour {
  public GameObject parentGameObject;
  public bool destoryOnDeactiveate = true;
  public eMemoryLevels targetMemoryLevel;

  //optimize particles settings
  
  public float targetFPS = 60.0 f; //What is your target frame rate?
  
  public float lossTolerance = 100.0 f; //what is the maximimum percentage of frame rate drop allowable?
 
  public bool optimize = false; //optimize particle system default: off
  
  public ParticleSystem myParticles; // drag your particle system here in inspector

  public static bool shouldShowDuringLock = false;  //Show if game is paused
  private int rate = 0;
  private int size = 1;

  // Do not show effects while spinning or whenever they are moving too fast to be seen.
  public static bool lockEffectShow = false;
  protected GameObject addedInstance;
  private bool instantiateObject = false;

  // Use this for initialization
  void OnEnable() {
   if (addedInstance == null && (shouldShowDuringLock || !lockEffectShow)) {
    if (instantiateObject) {
     addedInstance = GameObject.Instantiate(parentGameObject);
     addedInstance.transform.parent = this.transform;
     addedInstance.transform.localPosition = Vector3.zero;
     addedInstance.transform.localRotation = Quaternion.identity;
     addedInstance.transform.localScale = Vector3.one;
    }
   }
  }
  //When parent is disabled, object is destroyed
  void OnDisable() {
   if (destoryOnDeactiveate && addedInstance != null) {
    Destroy(addedInstance);
   }
  }


  void OnUpdate() {

   //monitor fps. If it drops below tolerance, remove a percentage of particle emmisions
   if (targetFPS < targetFPS / (lossTolerance * 0.01) && optimize)
    OptimizeParticles(0.1 f);
  }

  void OptimizeParticles(float scaler) {
   	float opScaler = scaler;
 
   	myParticles.emissionRate = (int) scaler;  // reduce emissions rate
   	myParticles.startSize = scaler; //reduce particle size
  	}
      }
   }
}