ClockStopper
ClockStopper is a Fabric server mod that halts the game's tick cycle while no players are online.
What it does
When the last player leaves, ClockStopper pauses the server's tick loop so the dedicated server stops consuming CPU. Crop growth and farm activity in spawn chunks also pause, and they resume once someone logs back in. The mod loads only on dedicated servers and is not loaded on the client.
Files target 1.21.1 and 1.21.11, with 1.0.1 for 1.21.11 as the latest Fabric build, published 2026-02-09. It is server-side only, so players join without installing anything, and it is released under the MIT License as open source.
Key features
Tick loop pausing
The server's tick cycle stops while no players are connected, and it resumes when a player joins.
Lower idle CPU use
With the tick loop halted, an empty server uses very little processor time and system resources.
Dedicated servers only
The mod loads on dedicated servers and is ignored by the client, so single-player worlds are not affected.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
AutoHibernate is also a server-side Fabric mod under the MIT License and open source, with files for 1.21.11 – 26.2. AutoServer is a server-side Fabric mod under the MIT License and open source, covering 1.7.2 – 1.21.10.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| ClockStopper | Fabric | 1.21.1 – 1.21.11 | Server-side only | 2026-02-09 |
| AutoHibernate | Fabric | 1.21.11 – 26.2 | Server-side only | 2026-09-12 |
| AutoServer | Fabric | 1.7.2 – 1.21.10 | Server-side only | 2025-10-30 |
Questions
Does ClockStopper need to be installed on players' computers?
Which versions does ClockStopper support?
In the catalog
ClockStopper is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 19,862 mods support Minecraft 1.21.11.
More from AlignedCookie88
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What the author says
A fabric mod that stops the game's tick cycle when no players are online. This allows the server to use practically zero system resources when no players are online. NOTE: This mod will ONLY load on DEDICATED SERVERS. This mod will not be loaded on the client.
Official listing
- Modrinth page
- modrinth.com/mod/clockstopper
- Owner
- AlignedCookie88
- Published
- 2024-08-13
- Updated on Modrinth
- 2026-02-09
- Facts verified
- 2026-10-15