Lag Spike Diary
by Gelzy
Lag Spike Diary records the state of a game around a stutter, so a player can send the details to a developer instead of describing the problem from memory.
What it does
Once installed in the mods folder, the Fabric mod starts with the game and works automatically. It watches frame rate, frametime and tick rate in real time, and when a freeze or a TPS spike occurs it saves a report that includes coordinates, movement speed and other details around the event. Reports are written as JSON files, which contain information about the system, the installed mods and the events that led up to the spike.
A player who notices a stutter can open the pause menu with the Escape key and press the report button, or use a hotkey, to attach the latest spike to a new report. Each report is written to a folder for lag spike reports, placed alongside the config files. The interface is written in English by default, and the mod works alongside Spark, showing hints when Spark is installed. Spark is a full profiler, and this mod does not replace it; its focus is quick creation of reports for developers.
Key features
Automatic freeze detection
Frame rate, frametime and tick rate are monitored continuously, and freezes and TPS spikes are detected without any action from the player.
Context capture
Coordinates, movement speed and other details are recorded around each spike, so the moment of the stutter is documented.
Detailed JSON reports
Each report lists system information, installed mods and events, written as JSON files in a folder next to the configs.
Pause menu access
Pause menu buttons and a hotkey let the player report the last spike in one step, without leaving the game.
Spark hints
When Spark is installed, the mod shows hints that point to Spark for deeper profiling.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Who it’s for: Players who want to send developers or server staff a precise record of a freeze, and developers who collect reports from testers on Fabric for 1.20.6.
How it compares
WhatsMyLag runs on Fabric and Quilt for 1.20 – 1.20.6 and can be installed on the client or the server; it is not open source and carries an All rights reserved license. Tick Stabilizer is server-side only for Fabric, covers 1.18 – 1.21.11 and is also not open source. Lag Spike Diary is client-side only and runs on Fabric for 1.20.1 – 1.20.6, which matches the first but not the server-side options.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Lag Spike Diary | Fabric | 1.20.1 – 1.20.6 | Client-side only | 2026-01-09 |
| WhatsMyLag | Fabric and Quilt | 1.20 – 1.20.6 | Client or server, optional | 2025-10-06 |
| Tick Stabilizer | Fabric | 1.18 – 1.21.11 | Server-side only | 2026-03-24 |
Questions
Does Lag Spike Diary need to be installed on the server?
Does Lag Spike Diary require Fabric API?
Where are the lag spike reports stored?
In the catalog
Lag Spike Diary is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 11,154 mods support Minecraft 1.20.6.
More from Gelzy
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What the author says
Lag Spike Diary is a "black box" for diagnosing lags in Minecraft. The mod automatically tracks FPS freezes and TPS spikes, saves detailed reports, and provides a convenient way to quickly attach diagnostics to an issue. Note: This mod does not replace Spark as a full-fledged profiler. It focuses on user-friendliness…
Official listing
- Modrinth page
- modrinth.com/mod/lag-spike-diary
- Owner
- Gelzy
- Published
- 2026-01-09
- Updated on Modrinth
- 2026-01-09
- Facts verified
- 2026-10-15