Fabric/Quilt Server Optimization

This has updated for 1.20.1, all of the optimization mods mentioned here are compatible with each other and don't affect vanilla behaviour by default.

Lithium - A mod designed to drastically improve the general performance of Minecraft without breaking things.

VMP - A mod designed to improve general server performance at high playercount.

C2ME - A mod designed to improve the performance of chunk generation, I/O, and loading. This is done by taking advantage of multiple CPU cores in parallel.

FerriteCore - A mod that reduces the memory usage of Minecraft in a few different ways.

Krypton - A mod that optimizes the Minecraft networking stack and entity tracker.

Async Locator - A mod that makes locating features asynchronous, mitigating associated lag.

RecipeCooldown - A mod that prevents excessive crafting recipe request from the client to lag out the server.

Carpet - A mod for vanilla Minecraft that allows you to take full control of what matters from a technical perspective of the game.

Carpet Extra - A mod that adds extra features to the Carpet mod.

Other useful mods

Chunky Pregenerator - A mod which pre-generates chunks, quickly and efficiently.

Spark - A performance profiler mod.

Gotta Go Fast = A simple mod that brings the bugfix for "Player moved too quickly!".

View Distance Fix - A mod that fixes the fog when having a higher render distance on the client than on the server. The server tricks the client into thinking that it has the same render distance as the client.

LibreExpFix - A small mod that fixes experience bug after teleporting across dimensions.

Ledger = A logging mod similar to CoreProtect.

bad packets - A library that allows packet messaging between different modding platforms. This means a Fabric client version of a mod that uses Bad Packets can send a packet to a server that uses the Forge version and vice versa.

Configurations

server.properties

sync-chunk-writes=false
simulation-distance should ideally be at least 8 if you want all types farms to work as intended

config/vmp.properties

use_async_chunks_on_some_commands=true
exp_use_optimized_chunk_ticking_iteration=true

world/carpet.conf

fastRedstoneDust true
lagFreeSpawning true

Java optimization

Since 1.18 Minecraft requires Java 17 to run. If you don't have Java 17 installed already you can get it from here

Java start-up flags

Generate a start-up script for your server here