ImmediatelyFast Modpack 1.19.3+ Mod [1.21.11, 1.21.10, 1.21.8]

ImmediatelyFast: Client-Side Rendering Optimization

ImmediatelyFast is an open-source Minecraft mod that boosts the performance of immediate mode rendering on the client side. Its lightweight design ensures broad compatibility with other modifications.

Optimized Rendering Components and Targeted Improvements

ImmediatelyFast optimizes all immediate mode rendering through a custom buffer implementation that batches draw calls and uploads data to the GPU more efficiently. The following immediate mode rendering areas are optimized:

• Entities
• Block entities
• Particles
• Text rendering
• GUI/HUD
• Immediate mode rendering of other mods

Additionally, the mod introduces targeted optimizations that replace vanilla rendering code with faster alternatives for these components:

• Map rendering
• HUD rendering
• Text rendering

Performance Benchmarks and Hardware Considerations

The following performance comparisons highlight areas where the mod excels. Note that if other mods appear in comparison tables, they also optimize that part of the game. Test hardware: Ryzen 5 1600, 32GB DDR4, GTX 1060. FPS numbers were obtained from external tools (e.g., MSI Afterburner) and averaged over several seconds. Keep in mind that ImmediatelyFast only improves FPS when the CPU is the bottleneck (likely unless using a very old GPU or heavy shaders). Slower CPUs benefit more than fast ones.

Entity Rendering: Up to 2x Higher FPS

On crowded servers, FPS typically doubles (tested with ImmediatelyFast 1.1.7 on Minecraft 1.19.3). The test environment was a Spigot server featuring 1,000 cows confined to a 3×3 box on screen.

Map Rendering: Up to 5x FPS Boost

When many maps are displayed simultaneously, FPS can increase by roughly five times (tested with ImmediatelyFast 1.1.1 on Minecraft 1.19.3). This benchmark used a Fabric server running the Image2Map mod with approximately 930 maps visible.

HUD Rendering: 40% FPS Improvement

In nearly all situations, FPS improves by approximately 40% (tested with ImmediatelyFast 1.1.7 on Minecraft 1.19.3). This test was performed on a Spigot server with various HUD elements visible: scoreboard, potion effect overlay, boss bars, filled chat, extra hearts, and a full hotbar.

Text Rendering Performance Gains

When many signs or holograms appear on screen, frame rates can roughly double. This was verified with ImmediatelyFast 1.1.7 on Minecraft 1.19.3.

Testing was carried out on a Spigot server with 200 signs (each filled with text) in view.

Block Entity Rendering FPS Improvement

With a large number of block entities visible, performance typically rises by about 20%. This result was obtained using ImmediatelyFast 1.1.7 on Minecraft 1.19.3.

Tests were conducted on a Spigot server where 400 chests were rendered on screen.

Mod Compatibility and Reported Issues

ImmediatelyFast is designed to minimise interference with other modifications. It should be compatible with the vast majority of mods and modpacks.

Known incompatibilities include:

• OptiFabric / OptiFine
• Most closed‑source clients such as LunarClient and LabyMod

If you find any problems, please report them through the project’s issue tracker.

Config

ImmediatelyFast has a config file which can be found in the config folder of your Minecraft instance. Most options should be left at their default values, but some may be tweaked to improve performance or compatibility.

font_atlas_resizing : Increases the sizes of the font atlas textures. This improves performance with high resolution or custom server fonts.
map_atlas_generation : Puts the map textures into a single texture instead of multiple textures. This improves performance when many maps are on screen.
hud_batching : Improves the performance of the HUD rendering by submitting less draw calls. If you experience issues with HUD elements, try disabling this optimization.
fast_text_lookup : Caches some data between rendering text characters. This slightly improves performance when rendering a lot of text.
avoid_redundant_framebuffer_switching : This optimization reduces the number of framebuffer switches when rendering many different things in the world (entities, particles, block entities, …) or the HUD to increase FPS.
experimental_disable_error_checking : Disables OpenGL error checking. This may improve performance on certain systems, but can cause hard to debug issues if enabled.
experimental_disable_resource_pack_conflict_handling : Controls if ImmediatelyFast should scan resource packs for incompatible core shader modifications in oder to disable some conflicting optimizations. This can be disabled to force optimizations even if they may cause graphical issues with certain resource packs.
experimental_sign_text_buffering : Buffers text on signs instead of re-rendering it every frame. May cause issues with high resolution or custom fonts.
experimental_screen_batching : Improves the performance of some in-game screens rendering by submitting less draw calls.

Developer API Documentation

The latest version of the API documentation can be viewed on the project website.

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