Why is my movement not smooth and jagged?

Question

My game isn't smooth, it runs at 60 fps but has quick lag spikes just under every second. I really can't figure out why. I have a feeling it's to do with my player movement code. My rigidbody's interpolation is set to interpolate, and collision detection to continuous. Here is a sample of what it looks like. https://gfycat.com/cleanmeagerhuemul

public ParticleSystem particleLauncher;

public float playerSpeed;
public float jumpSpeed;
public float coolDownTime = 2;
public CameraShake cameraShake;
public bool dashEnabled;
public bool isCamShakeEnabled;

private bool isJumping;
private float move;
private Rigidbody2D rb;
private bool facingRight;
private float nextDashTime = 0;

public bool movementAllowed;

private Animator anim;

// Start is called before the first frame update
void Start()
{
    isCamShakeEnabled = true;
    Scene currentScene = SceneManager.GetActiveScene();
    string sceneName = currentScene.name;
    dashEnabled = true;
    anim = GetComponent<Animator>();
    facingRight = true;
    rb = GetComponent<Rigidbody2D>();
}


void FixedUpdate()
{
    if(movementAllowed == true)
    if (Input.GetButtonDown("Jump") && !isJumping)
    {
        rb.AddForce(new Vector2(rb.velocity.x, jumpSpeed));
        isJumping = true;
    }
}
// Update is called once per frame
void Update()
{
    Application.targetFrameRate = 60;
    if (movementAllowed == true)
    {
        move = Input.GetAxisRaw("Horizontal");

        rb.velocity = new Vector2(move * playerSpeed, rb.velocity.y);


        if (isJumping == true)
        {
            anim.SetBool("isJumping", true);
        }
        if(isJumping == false)
        {
            anim.SetBool("isJumping", false);
        }


        Flip(move);

        if (move == 0)
        {
            anim.SetBool("isRunning", false);
        }
        else
        {
            anim.SetBool("isRunning", true);
        }

        if (Time.time > nextDashTime)
        {
            if (Input.GetButtonDown("Dash") && dashEnabled == true)
            {
                if(SceneManager.GetActiveScene() == SceneManager.GetSceneByName("Level4-2"))
                {
                    nextDashTime = Time.time + coolDownTime;
                    StartCoroutine("DashMove");
                }
                else
                {
                    nextDashTime = Time.time + coolDownTime;
                    StartCoroutine("DashMove");
                    StartCoroutine(cameraShake.Shake(.10f, .3f));
                }
            }
        }
    }

    if (SceneManager.GetActiveScene() == SceneManager.GetSceneByName ("Level5-4"))
    {
        dashEnabled = false;
        isCamShakeEnabled = false;
    }

    if (SceneManager.GetActiveScene() == SceneManager.GetSceneByName("Level5-4"))
    {
        isCamShakeEnabled = false;
    }
}



void OnTriggerEnter2D(Collider2D collision)
{
    if (collision.transform.CompareTag("killer"))
        gameObject.GetComponent<TrailRenderer>().enabled = false;
}




IEnumerator DashMove()
{
    playerSpeed += 60;
    particleLauncher.Emit(30);
    yield return new WaitForSeconds(.07f);
    playerSpeed -= 60;
}


void OnCollisionEnter2D(Collision2D other)
{
    if (other.gameObject.CompareTag("Ground"))
    {
        isJumping = false;
        gameObject.GetComponent<TrailRenderer>().enabled = true;
    }

    if (other.gameObject.CompareTag("BK"))
    {
        isJumping = false;
    }

    if (other.gameObject.CompareTag("MGround"))
    {
        this.transform.parent = other.transform;
        isJumping = false;
    }

    if (other.gameObject.CompareTag("Mcircle"))
    {
        this.transform.parent = other.transform;
        isJumping = false;
    }
}

void OnCollisionExit2D(Collision2D other)
{
    if (other.gameObject.CompareTag("MGround"))
    {
        this.transform.parent = null;
        isJumping = true;
    }

    if (other.gameObject.CompareTag("Mcircle"))
    {
        this.transform.parent = null;
        isJumping = true;
    }

    if (other.gameObject.CompareTag("Ground"))
    {
        isJumping = true;
    }

    if (other.gameObject.CompareTag("BK"))
    {
        isJumping = false;
    }
}

private void Flip(float move)
{
    if (move > 0 && !facingRight || move < 0 && facingRight)
    {
        facingRight = !facingRight;

        Vector3 theScale = transform.localScale;

        theScale.x *= -1;

        transform.localScale = theScale;
    }
}