C#

  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();
        }
    }
Mr. Burns

get all groups an their names
sort the names in descending length
foreach name check if replace.contains(${name}) [for groups like ${1} also check $1; for named groups also check the numbered Version]