Concerning links and images mostly, but not those which are explicitly enabled by Javascript on websites (certain webapps use drag and drop). I copy and paste a lot of text. The default drag and drop feature is really unhelpful, because it prevents text selection and causes unwanted accidental behaviors. Try to copy the text of one of the questions under "RELATED" on the right sidebar for example. It hardly is possible at all without straight out retyping the entire question, or opening the link and hoping that the title of the question on that page is not a link itself. Also once text is selected, you can drag-and-drop the text itself. Not only can this cause major slowdowns (also true to large images), but it also leads to accidental behavior in form text.