[Tkinter] Tk window not displaying until loop has completed

[Ganga]

OK. So, I added a root.update() inside the loops of my sample program which works to a point. It severely slows down the program though. Especially as it gets towards the end and there's more information to update. Isn't there a way to just update what is being added to the window, rather than updating the entire window every time through the loop?