Optimize resizing picture on a button with PIL - image

Question

self.image2Code:
from tkinter import *
from tkinter import font
from PIL import Image, ImageTk
class App(Tk):
def __init__(self):
Tk.__init__(self)
self.variables()
self.makeUI()
def variables(self):
self.buttonlist = []
self.font = font.Font(family = "Consolas", size = 12, weight = "bold")
def makeUI(self):
self.title("Changing font")
self.geometry("300x300")
self.minsize(200, 200)
self.maxsize(1000, 1000)
self.columnconfigure(0, weight = 1)
self.rowconfigure(0, weight = 1)
self.buttonlist.append(Button(self, height = 2, width = 4, font = self.font))
self.buttonlist[0].grid(row = 0, column = 0, sticky = W+E+S+N, padx = 2, pady = 2)
self.update()
self.image2 = Image.open("1.png")
self.image = ImageTk.PhotoImage(self.image2.resize((self.buttonlist[0].winfo_width(), self.buttonlist[0].winfo_height()), Image.ANTIALIAS))
self.buttonlist[0].configure(image = self.image)
self.buttonlist[0].bind("<Configure>", self.changeimage)
def changeimage(self, *args):
self.update()
#use smaller size
x = self.buttonlist[0].winfo_width()
y = self.buttonlist[0].winfo_height()
x = x if x < y else y
self.image = ImageTk.PhotoImage(self.image2.resize((x, x), Image.ANTIALIAS))
self.buttonlist[0].configure(image = self.image)
def main():
root = App()
root.mainloop()
if __name__ == "__main__":
main()
The problem:
The code works, the problem is that the program is slow on a quite powerful PC. It is making unnecessary calculations. My image is called "1.png".I don't know if I'm using the right approach.