C# 需不需要手动的去执行dispose及调用垃圾回收器，调用这些有什么优缺点？

  图片上传不上去。下面的代码是点击菜单栏，切换窗体。内存一直往上飙升？？只有打开注释的才好点。

做的东西模仿360的。上面是菜单栏，下面是功能块。功能块来回切换。

这种动态加载往主窗体panel中动态加载用户控件。感觉比较慢。有什么更好的解决方案。大侠指导一下啊

感激不尽
private void toolBar1_SelectedIndexChanged(object sender, EventArgs e)
        {
            //if (this.panelCenter.Controls.Count > 0)
            //{
            //    this.panelCenter.Controls[0].Dispose();
            //}
            this.panelCenter.Controls.Clear();
            //GC.Collect();
            switch (this.toolBar1.SelectedIndex)
            {
                case 0:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.Dail.GetInstence());
                    break;
                case 1:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.Knowlege.GetInstence());
                    break;
                case 2:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.NetWork.GetInstence());
                    break;
                case 3:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.Messge.GetInstence());
                    break;
                case 4:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.Bussiness.GetInstence());
                    break;
                case 5:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.ProcessManage.GetInstence());
                    break;
                case 6:
                    this.panelCenter.Controls.Add(TK_BroadBandClient.UseControl.Tool.GetInstence());
                    break;
            }
        }

补充：.NET技术 ,  C#