ImmediatelyFast in FTB StoneBlock 4

Same as in the All the Mons 1.3.0 guide

ImmediatelyFast is a client-side performance mod. It speeds up what Minecraft calls immediate mode rendering, which is a big part of how the game draws things on your screen every frame. It's built to be lightweight and to play nicely with other mods.^[1]

This pack ships ImmediatelyFast 1.6.13 for Minecraft 1.21.1 on NeoForge. It has been part of the pack since 0.3.0-beta or earlier.^[2]

What it speeds up

The mod uses a custom buffer implementation that batches draw calls and uploads data to the GPU more efficiently. That general optimization covers these areas:^[1]

• Entities^[1]
• Block entities^[1]
• Particles^[1]
• Text rendering^[1]
• GUI and HUD^[1]
• Immediate mode rendering done by other mods^[1]

It also replaces some vanilla rendering code with faster versions, specifically for map rendering, HUD rendering and text rendering.^[1]

Compatibility and config

The mod aims to interfere with other mods as little as possible and should work with most modpacks. Its known incompatibilities are OptiFabric/OptiFine and most closed source clients such as LunarClient and LabyMod.^[1]

It has a config file in the config folder of your instance. Most options are best left at their defaults, but a few can be tweaked for performance or compatibility. For example, if you see problems with HUD elements, the author suggests turning off the hud_batching optimization.^[1]

Same as in the All the Mods 10 8.1 guide

Good news: there's nothing to craft or set up first. ImmediatelyFast is a rendering optimization mod. It improves the immediate mode rendering performance of the client and is designed to be lightweight and compatible with other mods.^[1]

Unverified I couldn't confirm any items, recipes or quests for this mod in this pack, so there is no crafting order to follow and no recipe blocks to show.

What it speeds up

The mod uses a custom buffer implementation that batches draw calls and uploads data to the GPU more efficiently. That applies to these areas:^[1]

• Entities and block entities^[1]
• Particles^[1]
• Text rendering^[1]
• The GUI and HUD^[1]
• Immediate mode rendering from other mods^[1]

It also replaces some vanilla code with faster versions, specifically for map rendering, HUD rendering and text rendering.^[1]

What to expect

The mod only helps when your CPU is the bottleneck. That is most likely the case unless your GPU is ancient or you run very heavy shaders. Slower CPUs benefit more than really fast ones.^[1]

The mod's author reports the biggest gains in busy scenes: roughly 2x higher FPS with many entities or many signs around you, and roughly 5x higher with many maps on screen. Those figures were measured with older mod versions on Minecraft 1.19.3, not in this pack, so treat them as a rough guide to where the mod helps rather than what you'll see here.^[1]

Same as in the All the Mods 10 2.11 guide

ImmediatelyFast doesn't have machines, multiblocks, power or pipes. It's an open source performance mod that works entirely on the rendering side of your client. Its job is to make immediate mode rendering faster. That's the part of the game that draws things like mobs, chests, particles, text and your HUD every frame. It's designed to be lightweight and to play nicely with other mods.^[1]

How the batching works

The core trick is a custom buffer implementation. Normally the game sends many small draw calls. ImmediatelyFast batches those draw calls together and uploads data to your GPU more efficiently. This applies to immediate mode rendering in general, so it helps a whole range of things at once.^[1]

• Entities, such as mobs and animals.^[1]
• Block entities, such as chests.^[1]
• Particles.^[1]
• Text rendering.^[1]
• The GUI and HUD.^[1]
• Immediate mode rendering done by other mods, so modded blocks and entities can benefit too.^[1]

Targeted optimizations

On top of the general batching, ImmediatelyFast changes some vanilla rendering code to use a more efficient implementation. According to the mod page, these targeted changes cover three areas: map rendering, HUD rendering and text rendering. If you have a wall full of maps or a busy HUD, these are the parts doing the heavy lifting.^[1]

When you'll actually notice it

ImmediatelyFast can only raise your FPS when your CPU is the bottleneck. The mod page says this is most likely the case unless your GPU is very old or you run very heavy shaders. Slower CPUs benefit more than really fast ones. If you already have plenty of CPU headroom, you may not see much change.^[1]

The mod page's own benchmarks show the biggest gains in scenes packed with entities, maps, signs or HUD elements. For example, it expects around 2x higher FPS on busy servers with lots of entities and around 5x higher when many maps are on screen. Keep in mind that these tests were run on ImmediatelyFast 1.1.1 and 1.1.7 on Minecraft 1.19.3, not on the version in this pack. Treat them as a rough idea of where the mod helps, not as numbers you'll get here.^[1]

Compatibility

ImmediatelyFast is built to interfere with other mods as little as possible and should work with most mods and modpacks. The mod page lists OptiFabric and OptiFine as known incompatibilities, along with most closed source clients like LunarClient and LabyMod.^[1]

Config options

The mod has a config file in your instance's config folder. The mod page says most options should be left at their defaults, but some can be tweaked for performance or compatibility.^[1]

• font_atlas_resizing makes the font atlas textures larger, which helps with high resolution or custom server fonts.^[1]
• map_atlas_generation puts map textures into a single texture instead of many, which helps when lots of maps are on screen.^[1]
• hud_batching submits fewer draw calls for the HUD. If HUD elements look wrong, try turning this one off.^[1]
• fast_text_lookup caches some data between text characters, which slightly speeds up rendering large amounts of text.^[1]

Unverified This pack doesn't ship a config file for ImmediatelyFast, so it's unconfirmed which of these options are enabled by default in this version or whether the pack changes any of them.

ImmediatelyFast keeps all of its settings in one file, config/immediatelyfast.json. The good news is that this pack's setup is simple, and most of what you'd want is already switched on. Here's how the pack sets the options you're most likely to look at.^[3]

Turned on in this pack

• fast_buffer_upload is true.^[3]
• fast_text_lookup is true.^[3]
• font_atlas_resizing is true.^[3]
• map_atlas_generation is true.^[3]

Turned off in this pack

• hud_batching is false.^[3]
• experimental_screen_batching is false.^[3]
• experimental_sign_text_buffering is false.^[3]
• experimental_disable_error_checking and experimental_disable_resource_pack_conflict_handling are both false, so those safety checks stay active.^[3]

Debug options

Every debug option is false in this pack. That covers debug_only_and_not_recommended_disable_hardware_conflict_handling, debug_only_and_not_recommended_disable_mod_conflict_handling, debug_only_and_not_recommended_disable_universal_batching, debug_only_detailed_memory_leak_detection, debug_only_print_additional_error_information and debug_only_use_last_usage_for_batch_ordering. The file's own header for this group reads "Do not touch", so leave them alone unless you're chasing a specific bug.^[3]

dont_add_info_into_debug_hud is also false in the pack. The file's header for the cosmetic group says those values don't optimize anything.^[3]

Unverified The sources I have don't list the mod's default values, so I can't confirm which of these settings the pack changed from the default.

FTB StoneBlock 4 1.21.0 ships ImmediatelyFast 1.6.13+1.21.1. The mod has been in the pack since 1.0.0 or earlier. Below are the notable changes from the mod's own changelogs for the last few releases, newest first, up to the version you're running.^[4]

Unverified No pack changelog entries for ImmediatelyFast were available, so it is unverified whether the pack itself changed anything about this mod between releases.

Mod changelog highlights

• 1.6.13: restores the depth test state after flushing the DrawContext, which fixes a graphical issue with the Map Atlases mod. It also fixes an exception when closing unused buffers (this was a crash in the ATM10 modpack) and a config file handle leak.^[5]
• 1.6.12: a more compatible fix for item durability bar layering, which fixes an issue with Spectrum mod item slot decorations.^[6]
• 1.6.11: fixed the render order of the villager profession level layer.^[7]
• 1.6.10: fixed Iris shadow pass outline buffer clearing, which stops memory leaks with mods that render into the wrong buffer. It also fixes the villager type and profession layer render order, a bug in the core shader incompatibility detection logic, and adds an advanced memory leak detector.^[8]
• 1.6.9: made compatible with Java 25. It also clears the Iris shadow pass outline buffer in case mods render into the wrong buffer, which fixes a crash with glowing entities rendered with geckolib.^[9]
• 1.6.8: better compatibility with mods that don't render into the batching buffer while batching, which fixes a graphical issue with the AcceleratedRendering mod. It also fixes a potential performance issue with Iris.^[10]
• 1.6.7: fixed a crash when rendering outlined entities with a certain combination of mods.^[11]

The pattern is mostly compatibility and stability fixes with other rendering mods, plus some memory leak cleanup. The pack's 1.6.13 build includes all of them.^[4][5][8]