Recent patch has fixed Limit Break lags.
Now you can just pick Sammy with weapon limit = 1 on Hyper/Arcanas/Limit Break/Inverse and get 1kkk gold in ~7 min. Arcanas: Wicked Season / Disco of Gold.

https://store.steampowered.com/app/2313550/Vampire_Survivors_Tides_of_the_Foscari/
It unlocks when you reach level 20 in Mad Forest.
Sammy gains XP when picking up Gold Coins and Coin Bags.
Each gold is converted to exp 1:1, multiplied by the stage gold multiplier, Greed and Growth.
To unlock him, defeat 6000 Sammies (spawns at the Lake Foscari stage).
If having troubles finding them, check out the Lake Foscari map here:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2962309583
Wicked Season gives +0.5% Growth, Luck, Greed, and Curse every level (+ temporary doubles one of those stats every 10 seconds).
Disco of Gold makes us unkillable (picking up gold restores HP) and starts Gold Fever every time we pick up coin bag.
To unlock arcanas - find Randomazzo in Gallo Tower, north. Just follow the green arrow.
To unlock Wicked Season arcana - reach Level 50 with Christine.
To unlock Disco of Gold arcana - reach minute 31 in the Inlaid Library or defeat Death.

100% insta-kills enemies (if having 10k+ luck).
To unlock it - evolve the Shadow Servant.
You basically need to complete the DLC. If having troubles with it, check out my other guide:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2962309583
More enemies, more gold.
To unlock Hyper - Defeat Avatar of Gaea boss, that spawns at 25:00 (at Lake Foscari).
To unlock Inverse/Endless - select two dialogue options at the Eudaimonia Machine stage.
If having troubles with the basic game progression, check out my other guide:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2953930313
For obvious reasons.
Don't forget about the Charm PowerUp (unlocked by collecting the Apoplexy in Bat Country).
More Vicious Hunger projectiles => faster farming.
To unlock the Silent Old Sanctuary arcana - reach minute 31 in the Dairy Plant or defeat Death.
To unlock the Beginning arcana - reach Level 50 with Antonio.

• Set weapon limit to 2.
  
• Start the Lake Foscari stage with Hyper/Arcanas/Inverse/Endless modes as Sammy.
  * Do not enable Limit Break mode, cuz it makes the game unstable and causes significant FPS drop.
  
• Choose the Wicked Season as your starting arcana.
  
• Buy the Disco of Gold arcana from the merchant (available only with Inverse mode).
  
• Choose the Shadow Servant as your second weapon (on level-up).
  
• Pick up the free arcana chest (in the north-west forest) ASAP and choose the Silent Old Sanctuary arcana.
  
• Pick up some other stage items. My setup looked like this:
  

• Wait in the forest to delay item-pickup lag until you kill the first boss and get the Ophion.
  
• Return to the starting spot.
  
• Pick up boss-dropped arcana chest. Choose the Beginning arcana.
  * likely, you will encounter item-pickup lag, caused by high character level-up frequency (so, you will get no Candyboxes or arcanas from chests). In this case, you can buy the Beginning arcana from the merchant at 30:00.
  
• Wait as much as you want to farm.
  * Do not choose the Boogalo of Illusions, Lost & Found Painting or Chaos in the Dark Night arcanas (looks attractive, but causes significant FPS drop).

If you level-up too frequently, chest pick-ups will be delayed significantly. To avoid it and get the Ophion early, you can stay in the forest (where mushrooms spawns instead of normal enemies) until the first boss will be defeated and the Shadow Servant evolved.

Level-up frequency:

According to @Vermilisix, the game only lets you level up once every 4 frames.
I did some 5 min runs with different Target Framerate settings, that confirms, that your leveling (farming) speed is FPS-dependent:

* in this run in-game FPS was not consistent (140-240).

I did many test runs with different setups and stages.

I did 45 min 0 egg run and got 3 232 012 000 gold.
Got 1 000 000 000 gold at 26:39.
Got the Ophion at 4:50.
The run was smooth (60-143 FPS). Did it with 143 FPS limit.
Higher values expected with 240 FPS limit on a decent hardware.

Run stats:

---

I did 45 min 0 egg run and got 2 143 113 000 gold (which is slightly more than the Big Trouser gets per 760 min 0 egg afk run). In this case I got the Ophion from Candybox.

---

The run was smooth (60+ FPS), but suffered from the item-pickup lag, so I got the Ophion and the fourth arcana only at 28:52.

Check out my DLC-free farming guide:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2963344156