I play a round of golf walking with a caddie in just under two hours. The group I play with on Saturday mornings play in 3:30. We are walking.
Carts slow down golf because people sit their butts on them driving from ball to ball. Every course I play when in Utah people are on carts and not walking.
People sit on the tee asking who is up instead of someone just hitting.
People mark a one foot putt thinking they are emulating the pros. Putt out. The USGA recommends putting out unless you are in someone's line.
Play ready golf. If you are ready to hit your second shot and someone in your group is not go ahead and play.
None of us are playing for the cash the pros are but all to many amateur golfers try to act like the pros they see on TV and that slows down golf.
If it takes a foursome more than four hours to play a round of golf they should take up another sport, perhaps walking.