Could be an older "silent"mercury switch, in which a small pool of mercury completed the circuit when the switch handle was lifted to the up or 'on' position. These were sometimes known to slow with age as the mercury or it's pathway gradually deteriorated.
Mike
October 2013
could be loose wire in switch or the light fitting mate or the type of bulbs your using if its low energy ones
mm
February 2013
you are kidding aren't you?
Contact your electricity supplier and ask if they can speed up the delivery of electricity to your house see what they say.