Ok, I ran the numbers for the above file. I would like to point out that I was gunning for high score, along with a 6 condition victory, not communism, with the save. Failed the UN vote though

I did achieve researching all required techs and building all required components to meet the conditions though.
Notes: I ran the above save until population was maxxed in all cities, except the worker producers. (the tightly placed group of cities in the tundra) This was done to allow for a easy way of determining when the different governments were at an equal position because of the long duration of changing government types from the non-religious civ. Cities would lose between 3-5 population each. Tests were ran with ver 1.21.
Results:
Govt Waste Prod Corrupt Commerce
Communism 2289 1774 3647 3435
Monarchy 2670 1406 3899 3175
Democracy 2629 1437 6177 5261
Results after Forbidden Palace Destroyed
Govt Waste Prod Corrupt Commerce
Communism 2931 1106 4745 1298
Monarchy 3092 946 4352 2131
Democracy 3053 993 6984 3490
Very different than your results. In your test, Monarchy produced 98.6% of communism. Which I would agree isn't that much of a benefit- especially when the production is spread out. In my test it produces 79.3% of communism. That is a real benefit that unique play styles and stategies can be developed for.
The difference in results are? I don't know. I haven't seen a test map except for mine. I offered some things that could cause it, but none seem apply in this case.
Now for my analysis:
- Forbidden Palace. The Forbidden Palace does add a significant benefit to communism. In my test it affected communism the most, both numerically, and percentage wise. Communism was at 62% efficiency after the removal of it, while Monarchy was at 67% and Democracy was at 69%. This might be cause from the fact that I generally build the FP near a point where without a courthouse, the city has 95% corruption, but with a courthouse it has less corruption. This causes an area of overlapping affects, which means some of the potential of improvement is lost. I suspect the loss will be identical between Monarchy and Communism if an ideally placed FP was used- one that has zero area of overlapping influence.
- Build Times. The time to build improvements under communism that you would not normally build is minimal. It consists of building courthouses in your 14 core cities, the palace, forbidden palace, and 6 cities around each. (at least with how I layout cities) I would have already built courthouses in all other cities that aren't at 95% corruption, because you can generally build courthouse, temple, aqueduct, and marketplace. in less time than a temple, aqueduct, and a marketplace due to production improvements from the courthouse. The 14 cities take 4-5 turns for the most part. For the cities that are at 95% corruption, I will money hurry as many courthouses as my bankroll will allow the turn before I switch- keeping $1000 so that it collects interest. After I switch I will then build courthouses in the city's that don't have them yet. Since the cities are no longer at 95% corruption, I can build the courthouse, and a few improvements in the time it takes you to build one improvement.
- Size is important. Until you are at 2x optimal cities, production should be identical. Rounding, terrain improvements, and city placement would cause it to not be identical though. I suspect that the further over 2x the more noticable communism's benefits become- up to a point. SirPleb's test illustrates this. With over 10x optimal cities you reach a point were the average corruption for all your cities is 95%. At this point ANY government is better than communism. You aren't at this point at 6x optimal cities, as my game illustrates. Previous to the "95% corruption everywhere point" you will reach a point where, while you are producing more overall, it is so low in each individual city that it is in practice useless. Having 100 cities producing 2 shields isn't better than having 10 cities producing 10 shields and 100 producing 1. This point will also vary due to individual tastes and play styles though. I enjoyed the 46% corruption everywhere in my game. I also wouldn't call enough cities to cover 80% of the land mass on a huge, 60% water, pangea map a low number of cities. If you play a dense build game though, communism isn't a good choice though.
- Poprushing. Pre-Metropolis, I generally limit poprushing to "required" building improvements. Required are an aqueduct, a marketplace, and a hospital. At some point a temple will be produced to push the boundry out to 21 tiles as well. I generally will only poprush these if growth exceeds production. ie: A yellow 6 while building the aqueduct, unhappy people while building the marketplace, a yellow 12 while building the hospital, or stuck growth because of still being a 9 tile city. The 4 MP go a long ways overcoming hurt feelings from the aqueduct. The marketplace covers itself after one turn, you just need to make sure it isn't left revolting. Same with the hospital, just join enough slaves to work all tiles and make everyone happy. Post-Metropolis, I try to keep them a few population points below max. This keeps them producing everything that they can produce- shields, commerce, and population. Should I need something NOW, I poprush and add enough workers, changing them to entertainers to maintain complete happiness. This maintains WLTKD. Should a massive invasion occur (or I decide sporatically to have a huge Conscript Infantry/Mech Infantry invasion) where I need to draft from a lot of cities to repel the attack I have another tool at my fingertips listed in next section, happiness. Another plus is that for 10 shields worth of worker I receive 20 shields of rushed unit, while it takes 80 shields worth of commerce. Though shield/food/commerence exchange rates can't actually be taken literally, as it can depend on a lot of things.
- Happiness. There are 2 areas where communism excels at happiness. The one listed previously in this thread is the 4 MPs. Much better than Democracy and only 1 better than Monarchy. What does 1 better mean? Well, should you be good enough to have dominated the game by the 1400AD(NO, I am not that good . . . yet! ) and are milking the game, you can't use temples for the duration to make up the difference because you will have a culture win previous to 2050AD. Of course there are other ways to compensate, but ONLY one does have an impact. The second area where communism is better at happiness is the luxury slider. It works at a city level. When you put the slider to 10%, it goes to each city and moves 10% of the uncorrupted commerce to happiness, each unit of commerce producing a smiley. So under Monarchy, that 10% adds 3 smileys to your core cities and less as you move outwards. Your furthest cities receive ZERO smileys from it. You have to move the slider all the way to 30% before it produces 1 smiley at your most corrupted cities(while it produces 10 smileys in your core cities), the second smiley comes at 80%. What this means at a practical level is that in areas where happiness is easiest to compensate for by building improvements, it produces the most happiness, in areas where it is the most difficult to build improvements and most likely to culture flip, it provides the least improvement- needing at least 30% before it provides any. In contrast, 10% in my game produce a smiley in every metropolis, 20% provides 2. Draft two people from every city, go to 20% luxury to compensate.
- Research. Yes, it is faster with Democracy and Republic. 6 turn unknown research is the best I have achieved with Communism while I have hit the 4 turn roadblock several times with Democracies. The entire tree can be researched even under Cheiftain with it's slow speeds though. Just take out anyone that is building something you don't like
-Distributed Corruption. It does suffer when trying to build non-rushable big ticket items. ie: wonders. Though I have always managed to build Longevity, the one I want, if I try for it.(Some times I haven't managed to get through the tree quick enough for it to be worthwhile.) Just take out anyone that is building something you don't like :O
-Victory Conditions: It is mostly geared towards combat type finishes, though it is the second best choice for diplomatic victories. Only Democracy is less shunned than Communism and it comes in second- along wih all others except Democracy- for favored governments.
Summary: Communism's ability to use population as a very effective production method, better smiley production/control, and relatively equal/better (results vary) production makes it a very viable government. (Did you think I was going to say best? That depends too much on play styles and circumstances.) I do find it very useful when, after researching it, I expect a lot of combat, will want to develop conquered areas, and am trying for a high score. I think that more test cases need to be done in a controlled fashion so that different aspects can be determined. Why are our results so different? Is it terrain affecting it? Or is his test empire too small? Or perhaps Communism is only effective on huge maps? At what optimal city multiplier does corruption go to 95%? Is that on all size maps?
Chiefpaco, if you managed to get this far

, I plan on using a test map of seeded, railroaded, and irrigated grassland to try and answer some of the above questions.