How to check your Minecraft server health: TPS, tick time and spark

When players say your Minecraft server lags, you want a number, not a feeling. The Server health card on the Overview page shows how fast your server is ticking, with a graph of the last hours, and a button that profiles it for a minute and names the plugins or mods using the most time.

Open the card

Open your server in the panel and go to Overview. On Java Minecraft servers, the Server health card is under Usage. It shows a verdict in words:

TPS and tick time

Minecraft runs its world in ticks, and aims for 20 ticks per second (TPS). 20 is perfect, and below about 18 players start to notice lag. Each tick has 50 ms to finish, so you can read the same thing as Tick time (milliseconds per tick). Over 50 ms per tick the server falls behind and players feel lag. Use the switch above the graph to change between TPS and Tick time, and choose a window: Past hour, Past 6 hours or Past day. The caption under the headline number says which period it covers, and shows the slowest tick.

The panel sends a short command to the server once a minute while the card is open, so the graph has readings for the times the card was open. The commands and their answers are written to logs/latest.log.

When the card has no numbers

The card tells you why:

• Paused: nobody is online. Minecraft stops the world when it is empty, so there is nothing to measure.
• The server is not running. Start it to see how it ticks.
• This version of Minecraft cannot report its tick times by itself. The card offers Install spark, a free profiler from Modrinth. A restart follows, and measuring works after it.
• This version of Minecraft has no command that reports tick times. Vanilla added one in 1.20.3.
• The server did not answer the panel's tick check. A plugin may have replaced the /tps command. The panel tries again later.
• The world is frozen with /tick, so it is not ticking.
• Measuring. The first reading arrives within a minute.

Profile the lag with spark

TPS tells you that there is lag. A profile tells you where it comes from.

1. Wait for the lag to be happening, or ask players to do the thing that causes it.
2. On the card, under What slows it down, click Profile 60 s. It runs spark for one minute and shows Profiling with the seconds left.
3. When it finishes, the result says things like "Name used a share of the main thread. Minecraft itself used another share." It lists Plugins and mods, Minecraft itself and Busiest code, and what the server was doing during the profile: TPS, players online, entities and chunks loaded.
4. If one plugin or mod is the heaviest part, check what it is doing: a scheduled task, a big job such as world generation, or a setting that runs too often. Pause it or remove it, then profile again to compare. Earlier profiles are listed under Earlier profiles.

Vanilla cannot load a profiler. Paper, Fabric, Forge and NeoForge can. On Paper 1.21 and newer, spark is already included. On older versions, add the spark plugin to the plugins folder and restart the server.

Share a profile

Get a spark link uploads the profile to spark.lucko.me, a free public viewer run by the author of spark. Anyone with the link can open it, so the panel asks first (Get a spark link? and Upload and get the link). spark leaves passwords and the world seed out of it. Share the link with a plugin author when you ask for help. The server keeps its two newest profile files, so share a profile soon after you run it.

What to do next

• A slow server is often a server short of memory or with too much loaded. See How to reduce lag on your Minecraft server and How much RAM does a Minecraft server need.
• To see CPU, memory and storage, see How to read your server's usage graphs.
• If heavy generation is the cause, see How to pregenerate your Minecraft world so exploring does not lag.

If you have profiled and the lag stays, open a ticket and include the spark link.

Want a Minecraft server that keeps up? See Minecraft server hosting.