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Faster Iris Shadow Mapper [FISM]

Slightly improves the speed of Iris' shadow mapper. Built-in in Iris since Iris 1.11.2

FabricNeoForgeForgeQuilt
Loaders
FabricNeoForgeForgeQuilt
Downloads on Modrinth
918K
Followers on Modrinth
89
versions
35
Updated
September 20, 2026Sep 20
Published
in 2026
FISM logo — FISM logo · swipe

At a glance

Runs on Fabric, NeoForge, Forge and Quilt
For Minecraft 1.20.1, 1.21–26.3
Client only — no need to install it on the server
Latest version — 1.0.7 from September 20, 2026
Requires Fabric API
License MIT — free
Where it's needed
In gamerequiredOn servernot needed

Install in the game only; not needed on the server

Game versions1.20.1, 1.21–26.3

⚠️ This has been included in Iris 1.11.2, it is now only useful for older MC versions or for forks like oculus ⚠️

Faster Iris Shadow Mapping is a really lightweight mod that prevents unneeded things from rendering during the shadow pass.

This project does not replace Iris, both needs to be used at the same time for it to work.

This mod also works with oculus.

How it works

During the shadow pass, for opaque models, the color of the model won't have any visual change, a blue car and a red car both cast the same shadow, no matter their color. So what this mod does is it prevents things like the text on signs, the banner patterns, the enchantment glint etc from rendering during the shadow pass. It only improves performances when some of those are visibles.

Performance showcase

Small base in a flat world (26.1.2 - 1.0.0)
With / Without | 100FPS / 87FPS (avg) | 63FPS / 58 FPS (0.05% low)
With: 100FPS Without: 87FPS
  • +10% FPS
A lot of signs and banners (26.1.2 - 1.0.0)
With / Without | 15FPS / 9FPS (avg) | 10FPS / 1 FPS (0.05% low)
With: 15FPS Without: 9FP
  • +50% FPS on average
  • +1000% FPS on 0.05% low
  • The signs have text on them but on the other side

Modpacks

Feel free to use this mod in your modpacks without asking for permission.

FAQ

How to install Faster Iris Shadow Mapper [FISM]?

Install Fabric for your Minecraft version, download Faster Iris Shadow Mapper [FISM] for the same version and loader, put the file into the mods folder and launch the game with the loader profile.

Which Minecraft versions does Faster Iris Shadow Mapper [FISM] support?

Faster Iris Shadow Mapper [FISM] has builds for Minecraft 1.20.1, 1.21–26.3.

Is Faster Iris Shadow Mapper [FISM] needed on the server?

Client only — no need to install it on the server

License and source
MIT Licensefree to use and share with credit to the author
Original — Modrinth↗Files unchanged, verified with SHA-512Is this your mod? For rights holders

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