Calling richTextBox from other namespaces many times

In namespace WindowsApplication1 I declare the richTextBox1 which I want to CALL FROM OTHER NAMESPACES MANY TIMES MAKING CHANGES that I want TO STAY. How I could make it for maximum performance ? The first time I declared it as public static removing the keyword this in front of it. But every time I was going to the Form1.cs[Design]* and I was making just a little change to the richTextBox1 the static was leaving and the this was appearing again.(Can I stop it happens?) The second time I was passing the richTextBox1 as reference variable for many functions. But I think it is slow.(Is it realy slow?)