MsptMap

A per-chunk MSPT heatmap for Xaero's World Map. MsptMap shows which chunks are responsible for server-side lag, so you can find the culprit instead of guessing.

Features

• Per-chunk heatmap — chunks are coloured green → yellow → red according to the tick time they consume. Weakly-loaded chunks are shown in pale grey; heat colours can also be drawn on the Xaero minimap.
• Seven tick categories — random ticks, scheduled ticks, block updates, block events, block entities, entities and mob spawning are measured separately, and the tooltip shows which category the cost belongs to.
• Load source lookup — the load ticket behind each chunk is resolved: player_loading, forced, portal, ender_pearl, dragon and others. Chunks that hold a ticket are outlined in blue, and the tooltip reports the ticket name with the @x,z coordinates of the chunk on which the ticket resides.
• Scan overview — one panel reports total mspt, entity count, load sources and the five most costly chunks across all three dimensions. Select a row to move the map to that chunk.
• Optional monitoring — off by default. When enabled, the server watches MSPT and, on sustained overload, scans on its own and alerts online operators with a clickable list of the five most costly chunks.

Requirements

Supported versions

Note: 1.20.5, 1.20.6, 1.21.5 and 1.21.9 are not supported.

Installation

1. Install Fabric Loader for your Minecraft version.
2. Install Fabric API.
3. Place the MsptMap jar in the mods/ folder.
4. Install it on both the client and the server — sampling is performed on the server.

Single-player: the world is paused while the map is open. After selecting scan, close the map and wait for the result.

Usage

1. Open the world map and select the scan button in the upper-left corner.
2. Once sampling completes, chunks are coloured according to their tick cost: green → yellow → red; weakly-loaded chunks are pale grey.
3. Hovering over a chunk displays its coordinates, load level, load ticket, entity count, total mspt and a per-category breakdown.
4. The scan overview appears next to the scan button, reporting totals, load sources and the five most costly chunks. Selecting a row moves the map to that chunk; the source list can be expanded when there are many sources.
5. The ✕ button clears the heatmap.

Interpreting load tickets

The load ticket identifies the ticket that keeps the chunk loaded. The @x,z suffix gives the coordinates of the chunk on which the ticket resides. A chunk outlined in blue holds a ticket.

Note: games through 1.21.4 have no queryable ticket table, so the ticket name and its @x,z are not displayed there; only the load level is shown.

Commands

Scanning is limited to vanilla permission level 2 (operators) by default; /msptmap access <ops|all> opens it to every player or restores the default. The access and monitor subcommands are always restricted to operators.

Monitoring

Off by default. When enabled, once the server sees MSPT rise above the threshold, the five most costly chunks are sent to online operators as a chat alert; selecting a row opens the world map at that chunk.

Monitoring is switched with /msptmap monitor <on|off> and stored in config/msptmap-server.properties.

Configuration

Open Mod Menu → Settings, or select the settings button on the map. Settings are stored in config/msptmap-client.properties and can also be edited by hand.

Reset defaults restores all of the above to their default values.

License

MIT © 2026 Drizzle379

Bug reports and feature requests: GitHub Issues