Updated:
Which kind of lag?
| Symptom | Likely cause |
|---|---|
| Everyone lags at once; mobs stutter, crops and furnaces slow down | The server cannot keep up |
| One player lags; broken blocks reappear | That player's connection or computer |
| Terrain loads late when moving | Chunk generation or loading |
Measure it
A server runs 20 ticks per second (20 TPS). When one tick takes longer than 50 ms, TPS drops and everything slows.
- Java 1.20.3+:
/tick queryshows how long ticks take. See the tick command guide. - Paper and Spigot:
/tps. - A profiler such as spark shows exactly what uses the time.
Check 1: too many entities
/execute if entity @e[type=minecraft:item]The output is the number of dropped items. Thousands of them are a common cause, and /kill @e[type=minecraft:item] fixes it at once. Huge animal farms and mob storage also add up. The kill command guide has safer selectors.
Check 2: redstone
Clocks that never stop, large hopper chains and piston machines cost a lot. Turn off unused machines with a lever, and put a composter or similar block on top of hoppers that do not need to pull items.
Check 3: distance settings
Lower simulation-distance and view-distance in server.properties to process less of the world. The server.properties guide explains both.
Check 4: new chunk generation
Flying far with an elytra forces new terrain to generate. Pre-generate the world with a plugin such as Chunky, and limit the world with a world border.
Check 5: memory and server software
Too little RAM causes regular freezes. Check -Xmx in the start command. More is not always better; 4–6 GB is a sensible start for a small group. Optimized software such as Paper usually runs lighter than the vanilla server, though plugins and some behavior differ.
When only one player lags
Lower that player's render distance, use a wired connection instead of Wi-Fi, and check how far away the server is.
Common questions
- It suddenly got slow. Usually a new machine or a large breeding pen. Think about what changed just before and check that area.
- Will a bigger hosting plan fix it? Only if the CPU is the limit. Too many entities or redstone stay slow on any plan, so find the cause first.
- Bedrock servers? The same causes apply. Use
tick-distanceto set how far the world is simulated.
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