A Minecraft server runs 20 ticks per second; each tick has 50 ms of budget. When the work takes longer, TPS drops below 20 and everything on the server slows down: mobs stutter, blocks reappear, doors lag. That is server lag.
Three kinds of lag
| Symptom | Kind | Check |
|---|---|---|
| Everything slow for everyone, blocks come back after breaking | Server (TPS) | tps in console shows below 19 |
| Low frames, choppy picture, but chat and other players are fine | Client (FPS) | the player's F3 screen |
| Rubber-banding, delayed chat, one player only | Network (ping) | that player's ping in the tab list |
Read the numbers
Type tps in the console (Paper). 20.0 20.0 20.0 is perfect. Also useful: mspt (milliseconds per tick); under 50 is the goal, 30 leaves headroom.
The usual suspects, in order
- View distance too high: the single biggest lever. See players and view distance.
- Too many entities: mob farms, item drops on the floor, animals in a small space.
/minecraft:kill @e[type=item]clears dropped items instantly. - Chunk generation: players exploring new terrain. Pre-generate the world once.
- A plugin or mod doing too much every tick. Spark tells you which.
- Not enough RAM: the server spends its time in garbage collection. Console shows long GC pauses; upgrade.
Next: Read a Spark report.