- Open mod config (located in "...minecraft/config/betternether.json");
- Open "betternether.json" with text editor (I personally recommend Notepad++);
- Search in text to "global_plant_and_structures_density[def: 1.0]" and replace its value from 1.0 to 0.5 or 0.25 - this will reduce plants in world on generation;
- Search for "cities" and find "generate[def: true]" in figure brackets. Replace its value from true to false - this will disable nether cities generation, they are large and consume a lot of memory;
- Search for "terrain" and find "terrain_cleaning_pass[def: true]" and "world_fixing_pass[def: true]". Replace their values from true to false. This will disable world fixing passes - terrain became more weird, but worldgen will run faster.
All config changes requires game restart. I hope this will help you.

Nether Roads [1.16]
Nether Jungle Sounds
Flooded Deltas [1.16]
City Palettes And Procedural Destruction [1.16] (In Development)
Nether Jungle Overhaul [1.16]

4.1.4:
- fixed issues with wall connections;
- fixed /locate for cities;
- fixed ceiling structure generation;
- fixed chest of drawers rotations;
- fixed compatibility with KubeJS.
4.1.5:
- Fixed zero spacing error;
- Fixed server world save error;
- Fixed /locate command for cities.

4.1.6:
- Fixed locate command;
- Fixed mob groups;
- Fixed datapack & mod biomes structure compatibility;
- Fixed rare bedrock breaking by structures.

Where is config file?
It is in "config" folder (<minecraft_folder>/config/betternether.json). You can use "ModList" mod to see some config values in game, but not all (config is very large, it's hard to represent it full).
Here is information about JSON format.

Is this mod compatible with X mod?
Mod was designed to be compatible with others. If there is an issue - report it on GitHub.

Can you make version for X Minecraft?
Only for newer versions (later than 1.15 and for 1.15) and not immediately. Sometimes update is not required and last version works well.

Can you make forge version?
No, but if you really want it - you can make it by yourself and publish for others (MIT License). Porting such big mod to another modloader is a heavy task, due to not only large amount of code. It modified different game aspects - mushrooms growing on custom mycelium, maps rendering, fog distance, armor rendering fixes, recipe building, biomes modification etc, which is not possible with current Forge tools. It is possible to use third party libraries, but Forge code is much less stable than vanilla one and probably each new version will be incompatible with most code.

Will you continue 1.12 development?
No, 1.12 is not supported anymore. Last version is stable enough to play, development is focused on modern versions. If you have issues with 1.12 you can use information from "Some tips [1.12]" above.

Does mod have a wiki?
Yes, but it is very incomplete and a bit outdated. You can actually help with it. Here it is.

TheMinecraftOverlord
(the most detailed one)

Boodlyneck
(+ review of other good nether mods)