On PC during start-up, Windows generally loads a lot of programs, drivers etc. Drop-box is sort of a jumbo here, because it also has to wait to make a connection. Generally, many users often turn on a PC to quickly do something and waiting for 5 mins for computer to boot-up now (with SSD drives etc) is not an option. To achieve this, some programs go out of autostart. While there an option to make an executable and assign certain wait times, it surely would be a great option in dropbox.