Alistair Tait offers a radical approach to slow play on the PGA Tour.
Establish a fixed time to play a stipulated round. If courses such as Pebble Beach and St. Andrews can establish fixed times, then I'm sure tours around the world could do so on a daily basis. If a player – any player – comes in over that time they forfeit a stroke. For serious violations two strokes. The onus would then be on every player in the field to get around in good time.
The time doesn't have to be penal and can be adjusted daily taking into consideration factors such course difficulty and elements.
Radical? Yes, but desperate times demand desperate measures. We've put up with this cancer long enough.