As soon as the keeper has the ball in possession, a big countdown timer has to start behind the goal, counting down from 6 to zero. If the timer hits zero and the keeper still has the ball, a big noisy horn will sound and a free-kick is awarded. This will teach keepers from intentionally delaying the game if their team is ahead in the game. As a bonus, the crowd will have some entertainment as well.
A lot of teams that are in winning position (mostly in the second half of the game) are deliberately delaying the game. Most of the time the keeper has the best means to do this.
He will start to walk very slowly, bounces the ball way too many times. Starts waving at his players as if he has to wait until everybody has taken his place etc. etc.
This is very annoying and childish.
Don't delay, play goddammit!