Benefits of larger populations

The more people you have, the more tax-payers you have. So it definitely affects income. Not sure about manufacturing and research.

Max out your population on every planet and build out every planet with stock exchanges. Once you have cleared the tech tree, demolish every tech building you have and replace it with stock exchanges.
Your econ will be so extremely over the top, you will simply buy everything and anything you need.

Neilo is, sadly, quite correct.

I say "sadly" because I have never seen the AI react after completing research.

Thus, turning off the research victory allows the human player to outwait the AI for a path to victory.  That is, the AI will still be hobbled by those useless facilities (and even paying maintenance on them!) while the human builds them over with stock exchanges and/or factory-type buildings.

I've never seen the tech tree tapped out, or even anything close to it. However, I have seen one test game where an AI (the Yor, specifically) researched tech victory despite it being disabled, and after finishing it proceeded to return to research as normal.

You can still research tech victory in a game with tech victory turned off, it just won't trigger an endgame.

You should be able to max out the tech tree by end of year 1, IIRC, it has been a while since i played competitively.

You want to be building alot of tech, every bonus tile should be a NLC (or discovery sphere if you can't trade for NLC) and at least one planet, about +15 should do, as your tech cap. Every other planet max out with one farm, one VR and the rest stock exchanges.
Your econ will be FUBAR early game, but you will be teching so much that you will survive by trading techs for cash or planets.
^That ofc, is a very micro intensive gameplay, and if your looking to play the game "straight up" then you will need to balance alot more, but manu production is still over rated.

What tech speed is this? I don't play that way anyway, but no matter how much you micromanage I just don't see how it's possible to max out the tech tree when taking TA tech inflation into account, at least on the settings I use.

Very Fast tech, and yes its very possible, in fact it's all to easy. But like i said, its not the "normal" play style, its a style used to max your score, and involves quite alot. (its all here on the forums)
I don't play that way myself anymore, but once you have your tech really going, you research many, many techs per turn.
OFC, 700% libraries help too!

Ah, that clears it up. I've never played anything faster then Normal.

Unrelated note: What happened to the quote buttons?

Everything appears fine to me, browser refresh?

They're back now.

The AIs will finish all research on Suicidal, which is what I play, even at normal tech speeds.

I began to disable the research victory when I kept losing Suicidal games due to allies or multiple foes all generating the research victory imminent warning at the same time.

The one that finally made me do it was when one AI that I was at war with gave the warning, and I mobilized everything to take its last planet before the 10 turns were up.  Then, on the last turn, I got the same warning for an ally AI on the other side of the (largest DA size) galaxy.

When I first started playing DL's, I took the advice of the several guides available, and stayed away from developing farmland beyond "basic" and avoiding bonus farm tiles like the plague. I tried living off of trade which works until.....there are only several civs left and all become your enemies, leaving noone to trade with except minors (and maybe not even those if they are allied to a major).

 Then I started paying more attention to the "happiness" TG's, getting a political capital, and securing a morale resource mine whenever possible. This allowed for two things: larger populatons, and higher taxes. After I began praying for planets with a 100% farm bonus tile + a bonus happiness tile (or two), my money problems quickly disappeared.

 Unless a planet is of very low PQ with bonus tiles I need to take advantage of (like those 700% factory or research ones), every planet I own gets a Xeno Farm 1, at least. With my least populated planets at the 10b mark, and my most populated ones in the 16-22b range, my taxes alone cover my costs and trade is icing on the cake which I can afford to lose (though I keep my routes viable as long as I can). I have a ratio of one stock market for every 2 factory or research facility. So if a planet has 4 factories and two research facilities, that planet will get 3 stock markets....and if there isn't room to keep that ratio, I make room......

I can keep my planets healthy and happy, with no "unhappy faces" to deal with, even at the 22b mark.  

I'm currently in a game where I'm building 2 farms per planet or 1 on a bonus tile on PQ11 or above.  1 farm on PQ10 or below.  The green 100% tile is a target of mine, but I'll build on a yellow one as well.  Even on the low PQ planets, I'll build one farm on a bonus tile if it's there.  I generally research the farm techs to their max, although it's not a priority tech to get. 

I've found that pop and morale balance each other as long as you keep them in the middle range.  I keep my lowest approval planets at 20% or more and try to keep any PQ11+ under 6b pop at 100%.  I'm not concerned until my overall approval drops below 50% if my government has gotten above dictatorship.  

I never build a "happiness" building, but I'll leave it if there's already one there when I take the planet.  That is, until it's the last remaining non econ/farm or tech building.  Then I upgrade it to econ if I get to it.

I aim for 12 - 15 pop per planet later in the game, and do build a happiness building on each one.  I do that because I end up invading and invading on large maps, and I want the pop of the planets to recover by about the time another transport is built.