2D Object Spawn Lag

Hello. I'm extremely new to coding, and I'm having issues with a very simple minigame that I've created. The game, basically, is that you need to tap or click to spawn objects. Thats pretty much it. Once the player clicks or taps quickly, the game starts lagging. I thought that putting a time limit on the objects (so that they disappear after 2 seconds) would fix this--but it doesn't. I've attached the code below. Thanks.

using System.Collections; using System.Collections.Generic; using UnityEngine; // © 2017 TheFlyingKeyboard and released under MIT License // theflyingkeyboard.net public class SpawnOnClick : MonoBehaviour { public GameObject objectToSpawn; // Use this for initialization void Start () {

 }

 // Update is called once per frame
 void Update () {
     if (Input.GetMouseButtonDown(0))
     {
         Vector3 spawnPosition = Camera.main.ScreenToWorldPoint(Input.mousePosition);
         spawnPosition.z = 0.0f;
         GameObject objectInstance = Instantiate(objectToSpawn, spawnPosition, Quaternion.Euler(new Vector3(0, 0, 0)));
     }
 }

}

using UnityEngine; using System.Collections;

public class DestroyByTime : MonoBehaviour { public float lifetime;

 void Start ()
 {
     Destroy (gameObject, lifetime);
 }

}