There are no default background images in styles, but maybe you have installed this extension? In which case I suggested this modification to not have jerks when scrolling.
I do not see any particular slowdown with Chromium (I did not install Chrome). Try to disable the extensions one by one, and see if it changes anything after each deactivation.
Hello, Gaby. Can you tell me how to move the buttons under the message? As far as I understand, the _buttons.scss file is responsible for the position of the buttons, but I can't do it correctly.