ModsFinder

Faster Iris Shadow Mapper [FISM]

by maDU59_

With Faster Iris Shadow Mapper installed, Iris skips parts of the scene that do not need to be drawn during the shadow pass.

FabricForgeNeoForgeQuiltClient-side onlyMIT LicenseOpen source1.20.1 – 26.3

What it does

The mod is a lightweight client-side optimization that stops unneeded objects from rendering while the shadow map is built. It targets the shadow mapper that Iris already includes, so the shadow pass does less work per frame. It depends on Fabric API and is published for Fabric, Forge, NeoForge and Quilt.

The author reports a notable gain in scenes full of signs and banners. In one test scene the average frame rate rose from 9 to 15 frames per second, and the 0.05 percent low rose from 1 to 10. Other test figures in the listing show a 10 percent gain in general use. The mod also works with the Iris-compatible fork used on some loaders.

Files cover 1.20.1 – 26.3 across 18 release versions, with 1.0.7 for 26.3 as the latest Fabric and Quilt build. The code is open source under the MIT License, and the source code and issue tracker are linked from the project page. The mod runs on the client only, so servers do not need it.

Key features

  1. Shadow pass culling

    Objects that cannot cast a visible shadow are left out of the shadow render, which reduces the draw work.

  2. Sign and banner handling

    Signs and banners, which are costly to draw in large numbers, are handled so the shadow pass stays quick in dense builds.

  3. Iris fork support

    The same shadow pass changes apply when an Iris-compatible fork is used instead of Iris itself.

  4. Measured frame rate gains

    The author reports average and low frame rate changes in a sign and banner test scene, listed in the project description.

Compatibility

Latest build for each game version and loader.

26.x5 of 5 versions with builds
26.31.0.7Not availableNot available1.0.7
26.21.0.4Not availableNot available1.0.4
26.1.21.0.2Not available1.0.41.0.2
26.1.11.0.2Not available1.0.41.0.2
26.11.0.2Not available1.0.41.0.2
1.21.x12 of 12 versions with builds
1.21.111.0.2Not availableNot available1.0.2
1.21.101.0.2Not availableNot available1.0.2
1.21.91.0.2Not availableNot available1.0.2
1.21.81.0.2Not availableNot available1.0.2
1.21.71.0.2Not availableNot available1.0.2
1.21.61.0.2Not availableNot available1.0.2
1.21.51.0.2Not availableNot available1.0.2
1.21.41.0.2Not availableNot available1.0.2
1.21.31.0.2Not availableNot available1.0.2
1.21.21.0.2Not availableNot available1.0.2
1.21.11.0.5Not available1.0.51.0.5
1.211.0.5Not available1.0.51.0.5
1.20.x1 of 1 version with builds
ReleaseBetaAlphaNot available

Only full game releases are shown. This mod publishes no snapshot builds.

Requirements

Dependencies declared by the latest file for each loader.

Required 1

Fabric APILightweight and modular API providing common hooks and intercompatibility measures utilized by mods using the Fabric toolchain.
Required

Use cases

Dense builds with many signs

Players with large villages, shops or signage in view while using shaders can see the largest shadow pass cost reduced.

Shader packs with shadows enabled

The mod only affects the shadow pass, so it applies to any shader pack running on Iris or an Iris-compatible fork with shadows on.

Who it’s for: Players who run Iris with shaders and have frame rate drops in scenes with many signs, banners or other shadow-casting objects.

How it compares

Full comparison

Colorwheel is a client-side mod for Fabric, Forge and NeoForge covering 1.20.1 – 1.21.1 under the GNU Lesser General Public License v3.0 only. Sign Fix is a client-side Fabric mod for 1.21.5 – 26.2 released under CC0 1.0 Universal. Iris/Oculus & GeckoLib Compat is a client-side mod for Fabric, Forge and NeoForge covering 1.18.2 – 1.21 under the MIT License, and it addresses GeckoLib animations rather than shadow rendering.

ModLoadersGame versionsEnvironmentUpdated
Faster Iris Shadow Mapper [FISM]Fabric, Forge, NeoForge and Quilt1.20.1 – 26.3Client-side only2026-09-20
ColorwheelFabric, Forge and NeoForge1.20.1 – 1.21.1Client-side only2026-09-27
Sign FixFabric1.21.5 – 26.2Client-side only2026-03-25
Iris/Oculus & GeckoLib CompatFabric, Forge and NeoForge1.18.2 – 1.21Client-side only2024-03-16

Questions

Does Faster Iris Shadow Mapper need Fabric API?

Yes. Fabric API is the required dependency, so it must be installed alongside the mod on Fabric.

Does the mod need to be installed on a server?

No. It is installed on the player's side alone, so servers need nothing.

Which loader should be used?

The mod is published for Fabric, Forge, NeoForge and Quilt. Fabric and Quilt have the newest builds, up to 26.3, while Forge and NeoForge files cover earlier versions.

Does the mod work with Iris forks?

Yes. The author states that it works with an Iris-compatible fork in addition to Iris itself.

In the catalog

Faster Iris Shadow Mapper [FISM] is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 8,071 mods support Minecraft 26.3.

Optimization mods3,545Fabric modsMods for 26.38,071

More from maDU59_

All projects
Optimized Block Entities [OBE]1.20 – 26.3Fancy World Animations [FWA]1.20.1 – 26.3Projectile Trajectory Preview [PTP]1.21 – 26.3Fresh Loot Highlight [FLH]1.20 – 26.1.2Banner Hats1.21.3 – 1.21.11ClientSide Commands1.20 – 1.21.11

Similar mods

Sodium1.16.3 – 26.3Iris Shaders1.16.5 – 26.3Entity Cullingb1.7.3 – 26.3FerriteCore1.16.5 – 26.3ImmediatelyFast1.18.2 – 26.3Sodium Extra1.16.2 – 26.3

What the author says

Faster Iris Shadow Mapping is a really lightweight mod that prevents unneeded things from rendering during the shadow pass. A lot of signs and banners (26.1.2 - 1.0.0) With / Without | 15FPS / 9FPS (avg) | 10FPS / 1 FPS (0.05% low)
maDU59_, on the Modrinth page

Official listing

Owner
maDU59_
Published
2026-06-11
Updated on Modrinth
2026-09-20
Facts verified
2026-10-15

Tags

Optimization
Open on ModrinthCompare