Receipt printers in the UK universally print at the end of the checkout process. They're very fast - it only takes a few seconds to print a receipt about a foot

Receipt printers in the UK universally print at the end of the checkout process. They're very fast - it only takes a few seconds to print a receipt about a foot long. In addition, some supermarkets have a secondary printer which prints colour coupons at the same time at a similar speed. So, I don't think it would be a big slowdown.