Light Core

Light Core

LightCore is a client-side performance monitor that samples FPS and system memory/CPU usage, logs results, and ranks your Minecraft performance with tiers and insights.

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fabricoptimizationtechnologyutility
Configure a Compatible Minecraft Server

About this Mod

LightCore

LightCore is a lightweight, client-side performance logger for Minecraft that samples FPS and key system metrics, then converts them into a clear score, tier, and ranking—so you can understand what’s driving low performance.

What it measures

LightCore collects periodic performance snapshots containing:

  • Client FPS (averaged over a short rolling window)
  • JVM memory usage (heap used / heap max)
  • Physical memory usage (used / total)
  • CPU load (percent) and CPU core count
  • OS/architecture/Java version metadata (for context)

Scoring, tiers, and ranking

Each snapshot is analyzed into:

  • Score (0–100): a weighted evaluation based on FPS plus penalties from memory pressure, CPU load, and CPU core context
  • Tier: Excellent, Good, Average, or Low
  • Hint: a short, actionable message (e.g., low FPS, high CPU load, or high memory pressure)
  • Rank: where the current snapshot stands compared to recent history
    Sampling timing adapts to current conditions (when FPS is low, it samples more frequently; when FPS is stable, it backs off).

Output (CSV + logs)

Results are written to your local game directory as a CSV file:

  • logs/lightcore-performance.csv
    It also prints a compact summary line to logs for quick checks while testing.

How to use

  1. Install the mod on the client.
  2. Play normally for a few minutes (especially when you suspect lag/stutter).
  3. Review lightcore-performance.csv and the log output to spot trends and the best/worst snapshots.

Compatibility

Designed for Fabric with Fabric API and runs on the client side.

Available Versions

Light Core 0.0.1release
MC 1.21.4, 1.21.5, 1.21.6, 1.21.7, 1.21.8, 1.21.9, 1.21.10, 1.21.11fabric
March 20, 2026

How to Install Light Core on Your Client

1

Install the Mod Loader Locally

Install fabric for your local Minecraft version.

2

Download the Matching File

Choose the Light Core file for fabric and Minecraft 1.21.11.

3

Install Mod

Place the .jar file in your local .minecraft/mods folder and restart Minecraft. No server-side installation is required.

Compatibility

Mod Loaders

fabric

Minecraft Versions

1.21.11, 1.21.10, 1.21.9 (+5 more)

Server-side

Unsupported

Recommended RAM

4 GB(min. 3 GB)

Frequently Asked Questions

Does Light Core need to be installed on the Minecraft server?

No. Modrinth marks Light Core as unsupported on the server side. Install it only in your local Minecraft mods folder. Your server can remain unchanged unless the mod page lists an additional dependency.

Which version and loader does Light Core require?

Use a file for fabric and your exact Minecraft version. Supported versions include 1.21.11, 1.21.10, 1.21.9. Files for different loaders are not interchangeable.

Light Core is not working – what should I check?

First check the Minecraft version, loader version and required dependencies. Put the .jar file in your local .minecraft/mods folder and remove older duplicates. Because this mod is client-side, adding server RAM will not fix it.

Minecraft Server for Your Group

Light Core stays on your client. Host a compatible world for your group.

Recommended RAM
4 GBfrom €5.2/mo
Minimum 3 GB | per 8 players
Create Server Now
Client Compatibility Guide
NVMe SSD Storage
DDoS Protection included

Details

License
LicenseRef-All-Rights-Reserved
Server-side
Unsupported

Supported Versions

1.21.111.21.101.21.91.21.81.21.71.21.61.21.51.21.4