I think we're getting a bit too technical now
This coming from someone affliated with a virtual golf community on an internet forum from a site that hosts an online booking service.

Actually, I think that the majority of slow golfers don't actually realize they are slow. How often do you finish your round and check the time before going geez, 4:45 minutes that was slow.

Anything that can be done whether it be time deadlines, marshalls, clocks or gadgets to keep pace of play in people's heads during their round will help.