FPS Inspector

Find out which mod is eating your FPS! FPS Inspector watches your game while you play and tells you, in plain words, which mods cost you the most frames, what they were doing, and which one caused every lag spike. No flame graphs, no profiler knowledge needed!

Features

Overview

• Average FPS, 1% low FPS, frame time and spike count at a glance
• A live frame time graph, with slow frames in orange and spikes in red
• Your five heaviest mods, right on the first page!

Mods

• Every installed mod ranked by how much of the game's time it uses
• Milliseconds per frame for each mod
• A rough estimate of how many FPS each mod costs you
• What each mod was busy with: world rendering, chunk building, entities, block entities, HUD and menus, game ticking, networking, sound or particles
• Shows how much time goes to Minecraft itself and how much is spent waiting for your GPU or FPS limit

Spikes

• Every frame that took too long is recorded automatically
• Each spike shows how long it took, when it happened, and which mod was running during it!
• Finally know what causes that random stutter!

Frame graph overlay

• An optional small graph in any corner of your screen
• Shows your FPS, the current frame time, and names the mod behind the last spike

How to use

1. Press F8 (you can change this key) to open FPS Inspector
2. Play for a few seconds so it can collect data
3. Check the Overview, Mods and Spikes pages!

Settings

Open the settings from the menu itself, or through Mod Menu. You can change:

• The key that opens FPS Inspector (any letter, number or function key)
• Sampling on or off
• Sample rate: Light, Normal or Precise
• Analysis window: 10 seconds, 30 seconds, 1 minute or 2 minutes
• Spike threshold, from 20 to 250 ms
• Frame graph overlay on or off, and which corner it sits in
• Reset all collected measurements with one click

How it works

FPS Inspector checks what the game's main thread is doing many times per second and works out which mod that code belongs to. It also understands code that mods inject into Minecraft itself, so it can blame the right mod even then! Fabric API and bundled libraries are grouped under the mod players actually recognize.

Good to know: mods like Sodium do rendering work the game would do anyway, so they will always show up. That does not mean they are slowing you down!

Lightweight

Sampling runs on its own background thread and can be turned off completely in the settings. The Light sample rate keeps the overhead as low as possible!

Information

• Client side only! Nothing is needed on the server, so it works on any server and in singleplayer.
• Settings are saved in config/cookiefpsinspector.json
• Loader: Fabric
• Requires: Fabric API
• Optional: Mod Menu, for opening the settings from the mod list
• Versions: 1.21.11, 26.1, 26.1.1, 26.1.2, 26.2 and 26.3