Very Many Players (Fabric) Mod (1.21.11) – Improve Server Performance

Very Many Players (VMP) is a Fabric optimization mod that improves Minecraft server performance at high player counts by optimizing packet sending, entity tracking, and networking responsiveness.

Running a Minecraft server with dozens — or even hundreds — of concurrent players has always pushed vanilla code to its limits. The server struggles with entity lookups, chunk sending, and network overhead as the player count climbs. Very Many Players, commonly known as VMP, was built specifically to address these bottlenecks. Developed by ishland and the RelativityMC team, this mod has been downloaded over 11 million times on Modrinth since its initial release in December 2021, making it one of the most trusted server-side optimization mods in the Fabric ecosystem. The mod remains in active development, with updates landing as recently as March 2026 to support the latest Minecraft snapshots.

Key Features of Very Many Players

• Area Map Optimizations for Packet Sending and Player Lookups — On a vanilla server, every time the game needs to send packets to nearby players or look up who is in a certain area, it iterates through all online players. VMP replaces this with area maps, a spatial data structure that makes these lookups significantly faster. For servers with 50 or more players, this alone can noticeably reduce tick times.
• Cached Entity Trackers, Fluid States, and Ingredient Matching — The vanilla server recalculates entity tracking data, fluid block states, and crafting recipe ingredient matches more often than necessary. VMP introduces caching layers so these results are reused instead of recomputed every tick. This is especially beneficial during heavy crafting automation or in areas dense with entities like mob farms.
• Optimized Entity Collision Iteration — Collision checks are one of the most expensive operations on any busy server. When dozens of entities occupy the same space — think villager trading halls or animal farms — the server bogs down checking each pair. VMP optimizes how the server iterates through entities during collision detection, reducing the computational cost of crowded areas.
• Ticket Propagator Optimization via MCUtil — The chunk ticket propagator controls how chunks stay loaded around players and points of interest. VMP borrows an optimized implementation from the Paper project (licensed under MIT) to speed up this system. Faster ticket propagation means smoother chunk loading and unloading as players move through the world, which directly impacts how responsive the server feels.
• Java-Native Time Source — Vanilla Minecraft uses GLFW via JNI calls to get the current time, which adds unnecessary overhead on the client side. VMP switches to Java's built-in time source, removing the JNI call overhead entirely. While this is a client-side improvement, it contributes to a smoother overall experience when connecting to high-population servers.
• Custom Chunk Sending with Optional Rate-Limiting — VMP replaces the vanilla chunk sending mechanism with its own implementation that supports packet-level rate-limiting. This means the server can control how aggressively it sends chunk data to each player, preventing bandwidth spikes that cause lag for players with slower connections. Server operators can fine-tune this to match their network capacity.
• Per-Player Render Distance and Responsive TCP Connections — VMP adds packet-level per-player render distance, allowing the server to tailor how much world data each player receives. On top of that, it integrates packet priority concepts from the raknetify project to make vanilla TCP connections more responsive. This works best on direct connections without reverse proxies like Velocity or SSH port forwarding.

Screenshots

How to Install Very Many Players

1. Download and install Fabric Loader for your Minecraft server version. VMP supports versions from 1.20.6 through the latest 26.1 snapshots.
2. Download the correct VMP version for your Minecraft version from the official Modrinth page or the download section below.
3. Place the downloaded .jar file into your server's mods folder. VMP is a server-side mod, so players do not need to install anything on their clients.
4. For best results, also install Lithium alongside VMP — the mod author specifically recommends this combination for maximum performance gains.
5. Start your server. VMP applies its optimizations automatically with no configuration required for default usage.

Requirements & Compatibility

What's New

• Updated to support Minecraft 26.1-rc-3, the latest release candidate.
• Fixed CurseForge publishing Java version metadata for correct version targeting.
• Resolved a launch issue that could prevent the mod from initializing properly.
• Automated builds via GitHub Actions ensure faster releases aligned with new Minecraft snapshots.

Pros and Cons

Alternatives to Very Many Players

• Lithium — A general-purpose Fabric optimization mod that speeds up game logic including AI, physics, and world generation. Recommended to use alongside VMP for complementary performance gains.
• Krypton — Focuses specifically on Minecraft networking stack optimizations including packet compression and flush consolidation, making it a strong companion for servers with bandwidth constraints.
• C2ME (Concurrent Chunk Management Engine) — Parallelizes chunk generation and loading across multiple threads, targeting one of the biggest server bottlenecks when players explore new terrain.

Download Very Many Players

Frequently Asked Questions

Is Very Many Players a server-side or client-side mod?

It is primarily a server-side mod. You install VMP on the server and players connect with a completely vanilla client. The one client-side optimization — switching the time source from GLFW to Java's built-in source — is minor and does not require separate client installation in normal use.

Can I use VMP together with Lithium?

Yes — the VMP developer specifically recommends pairing it with Lithium for the best performance. The two mods optimize different areas of the game engine and do not conflict with each other. Lithium handles game logic like mob AI and block tick scheduling, while VMP focuses on player-scaling bottlenecks and networking.

Does VMP work with Velocity or other reverse proxies?

Partially. Most VMP optimizations work normally behind a reverse proxy, but the TCP responsiveness improvements that use packet priority from raknetify are less effective when traffic passes through Velocity or SSH port forwarding. If you use Velocity, you will still benefit from the entity tracking, area map, and chunk sending optimizations.

What Minecraft versions does Very Many Players support?

VMP supports Minecraft versions from 1.20.6 through 26.1-rc-3. The mod is updated frequently to keep pace with new Minecraft releases, including snapshots, pre-releases, and release candidates. Check the download section for the exact file matching your server version.

Will VMP change vanilla gameplay behavior?

No — VMP is designed to preserve vanilla functionality and behavior entirely. The mod only changes how the server processes internal operations like entity lookups, collision checks, and packet delivery. Players will not notice any gameplay differences other than improved performance and reduced lag on busy servers.

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