NoDelay

A client-side Fabric mod that disables Nagle's algorithm on your Minecraft connection and optionally tags packets for low-latency QoS — squeezing every wasted millisecond out of your trip to the server.

Supports Minecraft 1.21.10 and 1.21.11 · Fabric · Java 21 · Client-side only

What it does

Vanilla Minecraft leaves Nagle's algorithm enabled on its TCP socket. Nagle batches small outgoing packets to save bandwidth — great for downloading a movie, not great for a game where every keystroke is a 1-byte payload that needs to ship now. NoDelay sets TCP_NODELAY on the active server connection so packets go out the instant they're written, not 40 ms later when the kernel decides it has enough of them.

It also (optionally) sets the IP DSCP field to EF (Expedited Forwarding, 0xB8) so consumer routers and ISPs that honor QoS will prioritize your Minecraft traffic over background downloads.

Result: lower input-to-server latency, smoother PvP, fewer "rubberband when someone else on Wi-Fi opens YouTube" moments.

Features

TCP NoDelay — disables Nagle's algorithm on the live Netty channel
Low-latency DSCP marking — sets QoS class EF on outgoing packets
Login-phase application — applied before you even finish handshaking, not just in-game
Auto-reapply on reconnect — survives server hops without manual re-enabling
HUD badge — small "ND" indicator in your chosen corner so you know it's active. Compact, verbose, or dot-only styles, with X/Y nudge sliders
Toggle keybind — bound to O by default, fully rebindable, with on-screen toast feedback
Custom in-game settings UI — clean sidebar layout (Network / Display / Controls / About / Discord) with no Cloth or ModMenu dependency
/nodelay command — toggle, status, and settings shortcuts from the chat bar
First-time prompt — asks once when you first join a server, so you know the mod is there

Compatibility

Server-side: none required. NoDelay works on any vanilla or modded server. It's a pure transport-layer tweak — it doesn't touch game logic, packet contents, or anything an anti-cheat would care about.
Anti-cheat safe by design. NoDelay has no movement, combat, or rendering modifications. It just flips two socket options.
Standalone — no Fabric API tier-2 dependencies beyond the loader. No Cloth Config, no ModMenu required.

Requirements

Fabric Loader for the matching Minecraft version
Fabric API
Java 21

Default keybinds

Action	Default
Toggle NoDelay	`O`
Open settings	unbound

Both rebindable in the in-game menu under Controls.

Default settings

All toggles ship enabled out of the box, so a fresh install gives you the full latency reduction with zero configuration. If you want to A/B test the difference, just turn things off in the menu.

Community

Join the Discord: https://discord.gg/justiceclient

Credits

Made by mishka · MIT License