Totally Optimized FPS - Server Side

Alternate Current, reduces lag caused by redstone dust

AntiXray, helps server operators combat Xray users

Dynamic View, when the server is not lagging it increases the chunk view and simulation distance, once it goes over the given lag threshold it reduces the distance

Fabric API

Fabric Language Kotlin

Fabrication, a large collection of vanilla tweaks and small features , all completely configurable

Indium, an addon for the rendering optimisation mod Sodium

Krypton, attempts to optimize the Minecraft networking stack

Ksyxis, speeds up your world loading by not loading nearby chunks every time

LazyDFU, an optimization mod for Minecraft that defers unnecessary initialization work so that it is only performed if required

Lithium, a general-purpose optimisation mod for Minecraft which works to improve a number of systems (game physics, mob AI, block ticking, etc) without changing any behavior

Multiplayer Server Pause, simple utility mod that allows servers (including integrated servers) to pause when all connected clients are paused/on a pauseable screen

Phosphor, works to optimize one of game's most inefficient areas-- the lighting engine

QuickSpawns, adds two commands: /spawn to go to spawn ;  /setspawn to set spawn (as OP)

RandomPatches, adds, you guessed it, random patches

Smooth Boot , optimize Minecraft loading performance to be smoother on low end systems and scale better on high end systems

Sodium, greatly improves frame rates and stuttering while fixing many graphical issues

Spark, a performance profiler for Minecraft clients, servers and proxies

Xaero's Minimap, a map

Xaero's World Map, a map that shows you all of the areas that you have explored.