using Form does not release memory

In Microsoft Visual Studio Enterprise 2015 I have created the simplest Windows Forms Application (.NET Framework 4.5.2.):

On the main Form1 there's a button1. When you press it the Form2 opens and closes immediately and loops with this Form2 open and closure.

On Windows 10 Task Manager you will see the memory usage increasing :eek: . I expect the memory to be released instead . Obviously after some time the memory usage will be huge and cause problems. :thumbd:

It's a test that anyone can do. How can this be possible? Even if I decrease the loop and wait for the cycle to finish, the memory is not released.

Code:

---

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int loop = 100000;

            for (int i = 0; i < loop; i++)
            {
                using (Form2 a = new Form2())
                {
                    a.ShowDialog(this);
                }

                // Uncommenting the 2 following lines doesn't make any difference
                // GC.Collect();
                // GC.WaitForPendingFinalizers();
            }
        }
    }

    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            Close();
        }
    }

---