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Spark analyzer: why is my Minecraft server lagging?

Paste a Spark profile link or a .sparkprofile file to see what slows the server down and what to change in the config and start flags.

  • free, no sign-up
  • Paper, Purpur, Folia, Fabric, NeoForge, Forge
  • result kept for 30 days

Server profile

A profile link (spark) or a .sparkprofile file

Or drop a .sparkprofile, .sparkheap or .sparkhealth file here

Your plan's memory or the container limit. The profile does not include it (it only sees the whole machine's RAM), so without it we cannot tell if the heap is too large.

Create a profile with /spark profiler start and, after a few minutes, /spark profiler stop. We process it on our server and keep only the analysis result, without the author's name or JVM system properties, for 30 days.

spark-analyzer · —
  1. ready
  2. paste a profile link or choose a file
total—

How to find what causes server lag with spark

  1. Make sure the server has spark. Paper and Purpur have it built in from 1.21; on Fabric, Forge and NeoForge install the spark mod.

  2. While the server is lagging, run /spark profiler start and let the profile run for at least a few minutes.

  3. Stop it with /spark profiler stop and copy the link spark prints.

  4. Paste the link into the field or upload a .sparkprofile file. Fill in the server RAM to get heap advice too, then click “Analyse”.

  5. Go through the findings under “What to improve”, apply the changes from “Changes per file” to your config and restart the server.

About this tool

This Spark analyzer reads a profile from the spark plugin or mod and turns it into clear recommendations.

Paste a Spark profile link or upload a .sparkprofile file (.sparkheap and .sparkhealth work too) and see what slows your Minecraft server down: which plugins, entities or chunks take the most tick time, how TPS and MSPT look and whether the garbage collector is holding things up.

Each finding comes with concrete changes for your Paper config, server.properties and startup flags. The result gets a share link valid for 30 days.

Tool details
Input
link or file
Formats
.sparkprofile · .sparkheap · .sparkhealth
Size
up to 10 MB compressed
We keep
the result only, 30 days
Limit
8 analyses / 10 min

Frequently asked questions

Answers to the questions people ask most about this tool.

How do I create a Spark profile?

On a server with the spark plugin or mod run /spark profiler start, let it run for at least a few minutes, ideally while it lags, then run /spark profiler stop. Spark prints a link you can paste here.

Does it work for Fabric, Forge or a Velocity proxy?

Yes. On Fabric, Forge and NeoForge spark runs as a mod, and the analyzer shows the mods that load the main thread most instead of plugins. On a proxy the command is /sparkv (Velocity) or /sparkb (BungeeCord).

What do TPS and MSPT mean?

TPS is ticks per second (20 is ideal), MSPT is milliseconds per tick. Once MSPT goes above 50 ms the server can't keep up, TPS drops and players feel it as lag.

Do you store my profile?

We only store the analysis result so it can be shared by link, for 30 days. Shared results are not indexed by search engines.

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