Don't stay for hours or come right before closing time
A good restaurant should never do anything to make you feel rushed. However, you might take into consideration what happens when you linger for hours after your meal is done. See that mass of impatient people at the front waiting to be seated? You're not only keeping them waiting but also taking up a table in your server's section, which causes added stress for the hosts and prevents the server from making money (remember he or she depends on tips for compensation).
Also, don't arrive 10 minutes before the restaurant's closing time. This forces the kitchen staff to get everything dirty again (right after they've finished cleaning and organizing it all) and to take out food they've just put away. Plus, you're delaying the entire restaurant from closing on time and keeping the staff from being able to finish their shifts and go home.