FluidCore
by Emirique
FluidCore is a Fabric optimization mod that reduces the CPU cost of Minecraft's vanilla fluid tick system by letting idle fluid blocks sleep.
What it does
Vanilla Minecraft ticks every water and lava block on a regular schedule, even when a block has not changed for minutes and no player is near it. FluidCore puts such fluid blocks to sleep, so the server stops spending processing time on them. Both source blocks and flowing blocks are covered, and the mod is meant to keep the vanilla fluid behavior intact while doing so.
Sleeping fluids wake up instantly when a change reaches them, so the sleep system does not delay water or lava that is actually moving. Fluid blocks that are far from players and have stayed stable for a while are the first to sleep. Chunk unload cleanup removes the stored sleep data of fluid blocks in unloaded chunks. In a flat test world with a large body of water, the author measured a drop of 13% or more in CPU load, and that figure shifts with how complicated the world is.
FluidCore is published for Fabric 1.20.1 only, as a server-side only mod. Vanilla clients can join a server that runs it, and players in singleplayer can also use it. Fabric API is required. The code is licensed under the MIT License, and the project is not open source.
Key features
Distance-based sleeping
Fluid blocks farther from players are put to sleep first, so the blocks that matter most stay active.
Stability counter
A fluid block that has not changed for a set time is treated as stable and is eligible to sleep.
Event-driven wake-up
A change next to a sleeping fluid wakes it immediately, so water and lava keep flowing normally.
Chunk unload cleanup
Sleep data for fluid blocks is removed when their chunk unloads, so stored state does not accumulate.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Who it’s for: Server owners and singleplayer players on Fabric 1.20.1 who want to reduce the processing time that vanilla fluid ticks use. Players who need a client-side mod should look elsewhere, since FluidCore runs only on the server side.
How it compares
LazyFluids is also a Fabric mod for 1.20.1 that runs on the server side only and is released under the MIT License, but it is not open source. Krypton is a Fabric optimization for 1.16.2 – 26.3 that is open source under the GNU Lesser General Public License v3.0 only and can be installed on the client, the server or both.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| FluidCore | Fabric | 1.20.1 | Server-side only | 2026-07-01 |
| LazyFluids | Fabric | 1.20.1 | Server-side only | 2025-08-27 |
| Krypton | Fabric | 1.16.2 – 26.3 | Client or server, optional | 2026-09-30 |
Questions
Does FluidCore need Fabric API?
Do players have to install FluidCore?
Will FluidCore change how water and lava behave?
In the catalog
FluidCore is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 34,764 mods support Minecraft 1.20.1.
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What the author says
FluidCore is a lightweight Fabric performance mod that optimizes Minecraft's vanilla fluid tick system for both singleplayer and multiplayer servers. Vanilla Minecraft ticks every single water and lava block every few game ticks — even blocks that haven't changed in minutes, and even when no player is nearby…
Official listing
- Modrinth page
- modrinth.com/mod/fluidcore
- Owner
- Emirique
- Published
- 2026-07-01
- Updated on Modrinth
- 2026-07-01
- Facts verified
- 2026-10-15