My chart is slow down after some

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace chart
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        double a,b,c = 0;
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        
        private void timer1_Tick(object sender, EventArgs e)
        {
            a = a + 1;
            b = b + 3;
            timervaluee.Text=a.ToString()+ "," + b.ToString()+ "," + c.ToString();
            chart1.Series[0].Points.AddXY(a, b);
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
                timer1.Start();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            chart1.Series[0].Points.Clear();           
        }

        private void button3_Click(object sender, EventArgs e)
        {
            timer1.Stop();
        }
    }
}