Remember the old days when the invoices were printed on paper that already contained the company logo, headers and footers?
The main reason for using pre-printed paper was the processing speed - you don't have to print that for every page. You will also save money because pre-printed paper is printed using an offset process (think newspapers) that is costs less.
Using the latest rendering engines you can achieve the same effect - a smart rendering engine will create an "overlay" that is cached in the printer's memory and printed very efficiently.
