I frequently play by myself. I try to play at off times. Used to play at all private club and more recently started playing at semi-private. I am patient knowing that my 1:30 round is very fast. Most people (especially because they know me) rarely have a problem letting me slide through. Worst case, I'll skip up a hole if there is room. But the a-holes that don't let anyone play through or think that singles have no rights when there are 3 holes open in front of them might deserve being hit into. In any event, I find there are a few types of problem slow-players: unskilled and uneducated, low-skill and trying, and usually skilled but arrogant. Descriptions and solutions follow:
Unskilled/uneducated: Can't blame them. They just don't know. I remember being a 30+ hcp before being a 4. I've seen kids trying to be respectful rushing their putts or picking up 20 footers. When I play through, I tell them they have a right to enjoy their round and further tell them about proper ways to let people play through. They should have fun and not worry about me staring them down from 85yds out just to have me wait on the next tee bc they're 160yds down the fairway rushing again. Solution: first, have either days or times where you let better golfers go off first. The weekly foursome of single digit handicappers have priority from 7am to 9am so the whole field isn't backed up. Maybe have a prebooking rule that low handicap or singles can go book 7 days in advance versus 4 for others. The proshop should screen unknown golfers. If they are 20+ hcp, just rattle off some etiquette rules before they go out. "We focus on pace of play for everyone's enjoyment. If you have room in front of you and a group or a single is waiting on you, please let them play through." And don't blame women for slow play. Many are great golfers. If they suck, then they might just fall into the general "unskilled/uneducated" category. And then have marshals enforce the pace of play policy...
Low-skill/trying: This might be your group of once a month golfers, a mixed-group of men and women or kids, older guys trying to break 100, a business outing with a few sandbaggers and a noobie, or whatever. It's great seeing these guys out enjoying the game. Many of them take it kind of seriously, low-stakes wagering, or whatever. The problem is they drive about 200 but, like someone else mentioned, think they drive 300 so they wait for the fairway to clear. But they're trying. Of course, the other problem is they drive it just long enough to go deep in the woods. At least the ladies with the 120y drives are just dinking it down the middle of the fairway. These are typically the people who might not be playing ready golf or often spend 5 minutes a hole looking for balls. I remember gauging my game's improvement not by my score but by the number of balls I lost. Probably the single best piece of advice for them to speed play is to limit time looking for balls, play provisionals, and let other groups play through if you're going to spend the 5 minutes looking. And since within your foursome you're probably going to look for balls for 30 minutes per round, that's a large part of the delays. Solution: pro shop/marshals watch for lost ball/play through etiquette. Maybe have cards on the carts with a few etiquette tips like for lost balls.
Skilled but arrogant: Several groups of old stogy men at my private club thought they owned the course. They probably used to be great golfers. Now they are older and slower. One guy (on the board with me) said "a round of golf should take as long as it takes to get through a fifth of whiskey". He didn't mind 5 hour rounds. He was still single digit hcp, but wasn't in a hurry for anyone. One day I was a single coming up behind him around dusk. I was stuck behind him on 17 (par 3). He didn't let me through there or on 18. He was with another guy and their two wives. Took about 30 minutes for those last two holes. Of course, I couldn't hit my approach on a reachable par 5 for 10 minutes while they hit 3 (or more) on and putted out. It was too dark to see my approach by then so I just hit and hoped. All they had to do was let me play in with them or let me tee off on 18. I'd have been out of their way in 3 minutes. None of them could have reached me on my drive so they could hit away as soon as I got to my ball. Would have cost them maybe 3 minutes of waiting and not affected them at all plus I'd have finished my round appropriately. Often these cocky young guys or stogy old guys don't want to respect smaller, better, or faster groups. They KNOW the rules. They just don't care. I think these are the worst of the slow-play offenders. And, like the guy in my story, what are you going to do? He's on the board (as was I). The pro isn't going to cross him. I guess just beat him at the member-guest or the next skins game. In general, though, hopefully you have a pro that will talk with members or other offenders who think they own the course and have no reason to not let people play through (or play in with them).
Having said all that, if the course if fairly full and there isn't room to play through anyway, faster groups have to learn to just deal with it. Full courses only move as fast as the slowest group. Outside of the marshals doing their jobs, the other option includes smaller groups joining up. When I was a single, if I ran into heavy traffic, I'd just play two or three balls or work on my putting (if nobody was waiting) or I'd join up with other guys and then be patient if they were hackers. In the end, it's all about respect. More golfers need to respect other people on the course whether thats being patient with noobies or letting smaller/faster/better groups play through.