Great questions there. The page builder does not add much in the way of load time or bloat. One of the reasons I choose to work with this one is because it was very lightweight. It will have minimal impact on the load time of a page.
For the padding on a full width page, you could try something like this in the Custom CSS found in the advanced section of the customizer:
If you haven’t used it before vw is a unit of measure based on the width of the browser window (viewport width). As the window gets wider, it increases in size too. It works similar to how a percentage measure works.
Feel free to swap that out for whatever works for you.