//How to stop flickering
//This answer is same for PictureBox, Form, Panel and etc.

//First, add this library.
using System.Reflection;

//change "MyPanel" with your panel name.
 typeof(Panel).InvokeMember("DoubleBuffered", BindingFlags.SetProperty| BindingFlags.Instance | BindingFlags.NonPublic, null,  MyPanel  , new object[] { true });