slowness in typing and deleting characters using backspace in wpf textbox control

In wpf, when I drag/drop a textbox on an empty window and run the application the typing and deleting of characters using backspace is very开发者_如何学Go fast but when I have a large number of controls (around 200+ controls) on a window the typing and deleting of characters using backspace is slow. Especially deleting using backspace. Also rendering of the window becomes slow. Can anybody tell me what is wrong here?

Note: 1. My operating system is Windows XP (just in case there is a dependency) 2. I have not handled any event of any control. Neither have I added any attribute/event to the window. It is just the default properties of the windows. Please do let me know if I am suppose to add any to make this work