I often start to read a huge file and then want to quit after a while, but there is a lag from pressing Ctrl+C to the program stops. Is there a chance of shortening the lag by pressing the Ctrl+C key several times? Or am I wasting my keypresses?
Does pressing ctrl-c several times make the running program close more quickly?
process;kill;signals
After the first Ctrl-C, the program will receive SIGINT and usually starts cleaning up (deleting tmp files, closing sockets, etc.). If you hit Ctrl-C again while that is going on, it may happen that you interrupt the clean up routine (i.e. the additional signal might be acted upon instead of being left alone), leaving a mess behind. While this usually is not the case, more commonly the additional signals are in fact sent after the process finished (because of the inherent delays in the interaction of the operator with the system). That means that signals are received by another process (often shell, but not always). If that recipient doesn't handle this signal properly (like shell usually does - see Jenny D's answer) you may be unpleasantly surprised by the outcome of such an action.