Investigate Minecraft lag: TPS, MSPT, and “Can’t keep up”

Distinguish tick lag from connection problems

When admins say “the server lags”, they often mix several problems together:

• low TPS
• high MSPT
• chunk generation spikes
• plugin slowdowns
• network problems that only feel like lag

For tick performance:

• the server tries to run 20 ticks per second
• that means it has 50 ms per tick on average

If your average tick time exceeds that budget, TPS begins to fall and the server may log messages such as Can't keep up!.

What TPS and MSPT actually tell you

TPS

TPS means ticks per second. At the target rate, the server reaches 20 TPS.

MSPT

MSPT means milliseconds per tick. This is often the more actionable number because it shows how much time the server needs to process game logic.

As a practical rule:

• around or below 50 ms average tick time is where the server can still sustain 20 TPS
• above that, the server begins to fall behind

First checks before you change any settings

Do these in order:

1. confirm that the issue is active right now
2. measure instead of guessing
3. change one thing at a time

On Paper 1.21 and newer, start with Spark because it is bundled and is the preferred profiler:

/spark tps
/spark profiler start --timeout 600

If you are not on Paper yet, read Paper vs Vanilla vs Fabric vs Forge before assuming your current server software is the best base for performance work.

The usual causes of lag

1. CPU-bound ticks

Minecraft server work is still very sensitive to single-thread performance. More RAM does not shorten CPU-bound tick work.

2. Chunk generation and exploration

Fast exploration creates chunk generation work. This often appears as spikes instead of constant low TPS.

3. Too much simulation

Paper documents simulation-distance separately from view-distance. That matters because entity ticking and active game logic are not the same as what the client can see.

4. Plugin or mod behavior

A plugin or scheduled task can consume a large part of the tick time.

5. Entity-heavy farms and villages

Large mob farms, dense villager trading halls, and constant hopper activity can dominate tick time.

Safe fix order

Do not start with random config packs. The safer order is:

1. measure with Spark
2. identify whether the issue is persistent or spiky
3. reduce the most expensive source first
4. only then tune Paper distances

Fast decisions that are usually safe

• reduce simulation-distance when active simulation causes the load
• keep view-distance reasonable for your player count and hardware
• test changes during the actual lag scenario, not only on an empty server

For concrete values, continue with View Distance vs Simulation Distance: Safe Starting Values for Paper.

Common mistakes