Style cause lagging

I made a GUI with buttons, image, treeview, entries, scrollbars, comboboxes, listboxes. My program start lagging when I drag and move the root window. I had no idea what cause this issue then I turned off the light-forest theme and the lagg gone. Has anybody noticed something similar?

That is a common issue with tkinter. Complexity often makes tk lag while rendering the icons and images of GUI elements.