Too many delay after adding a user with Firebase authentication in Android Studio

class SignUpActivity : AppCompatActivity() {
private lateinit var auth: FirebaseAuth
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_sign_up)

    auth= Firebase.auth
    initSignUpButton()
}
private fun initSignUpButton(){
    val signUpButton= findViewById<AppCompatButton>(R.id.signUpButton)
    signUpButton.setOnClickListener {
        val email= getInputEmail()
        val password= getInputPassword()
        auth.createUserWithEmailAndPassword(email,password)
            .addOnCompleteListener(this){ task ->
                if(task.isSuccessful){
                    Toast.makeText(this, "completed to sign up.", Toast.LENGTH_SHORT).show()
                    startActivity(Intent(this, LoginActivity::class.java))
                    // finish()
                }else {
                    Toast.makeText(this, "failed to sign up!", Toast.LENGTH_SHORT).show()
                }
            }
    }
}

private fun getInputEmail(): String{
    return findViewById<EditText>(R.id.inputEmailEditText).text.toString()
}
private fun getInputPassword(): String{
    return findViewById<EditText>(R.id.inputPasswordEditText).text.toString()
}
}

After I push signup button, Toast message showed up in about 4minutes and user added too Not right after I pushed sign up button. I don't know why this is happened to me.

enter image description here - After push sign up button
(In 4mins..) enter image description here - User added.

enter image description here -Layout

[Clicked signup button-> (4mins...) -> user added..] -result..
[Clicked signup button-> (1sec...) -> user added..] -I wish