My Minecraft server lags — find the cause with Spark

If your console says Can't keep up! Is the server overloaded?, record the lag while it happens. Spark gives you a report to use when checking your world, plugins or modpack.

What you'll do

1. 1Open the server console
2. 2Record the lag with Spark
3. 3Check what was busy
4. 4Apply one fix and test again

This walkthrough uses Paper or Purpur

Spark is bundled with Paper and Purpur, as described in our performance guide. For a modded server, check how Spark is installed for your server software before using these commands.

Find the cause with Spark

1. Open the console while the lag happens

   Log in to the game panel and open your server’s Console. Note whether everyone lags, whether it happens only near a base, or whether it starts while exploring new terrain. A location-specific problem gives you a place to investigate; it does not identify the cause by itself.

2. Start a Spark recording

   Enter spark profiler start in the console. Keep the server running and let players reproduce the lag for a few minutes. A recording taken while the server is idle will miss the problem.

3. Stop the recording and open the report

   Enter spark profiler stop in the console. Open the link Spark prints. Keep that link if you need help from support.

4. Check the busiest work

   Look for whether the report points to entities, chunk or world generation, or a plugin or mod. Use that finding as a lead: a busy mod or plugin in the report needs a closer look, but the report alone does not prove that your hosting plan is too small.

5. Change one thing and test again

   If chunks or many active areas are the issue, try view-distance=6 and simulation-distance=4 in server.properties using the file manager. Restart, then record the same situation again. For an entity-heavy base, reduce the mobs in that area. If a plugin or mod dominates the report, update or temporarily remove it and test again. See performance settings for the config and chunk pre-generation steps.

Done! You have a report and a test result

If the lag remains, open a support ticket with the Spark link, when the lag happens and what you already changed. We can use that evidence to discuss whether your setup or the server needs more resources.

Extra tips

• Can't keep up! is a clue: Match the warning to a Spark recording made at the same time; the warning alone does not identify the culprit.
• Lag near a base: Check the report for entity work, then test with fewer mobs in that area.
• Lag while exploring: New chunk generation can cause spikes; the performance guide covers pre-generating the world.
• Still unclear? Include the report link and the exact console warning in your ticket.

Still stuck?

Send us your server name and the last 20 console lines. A real person reads it, usually within a few hours.

Open a ticket

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