Iron Backpacks (Unofficial Port)

Iron Backpacks 1.0.2 for Minecraft 1.21.1 — a performance update for NeoForge and Fabric.

Install: drop the jar for your loader into the mods folder (server and every client); JEI is optional. Worlds and backpacks from 1.0.1 load as they are.

Changes

• Faster rendering of backpacks. Every frame the game asks each item for its name (for items lying on the ground) and each inventory icon for its durability bar; backpacks answered by rebuilding their whole inventory each time. Now they read only what is needed:
  • 400 full backpacks lying on the ground: 140 → 190 FPS;
  • 36 full backpacks in an open inventory: from 69 % to 76 % of the frame rate of the same number of shulker boxes; with the damage bar upgrade from 52 % to 62 %.
• Lighter backpack models. The border and latch layers, which always have the same colour, are merged into one texture: the backpacks look exactly the same (checked pixel by pixel, dyed and undyed), with a third fewer vertices.
• No gameplay changes; the server side was already as light as vanilla.

17 in-game tests pass on NeoForge and on Fabric, also with the Fabric release jar on a real server.

Differences from 1.12.2 and the measurements: PORTLOG.md.