Why is Minecraft broken on PC (Java)? (Lag and memory pressure on large worlds)
Frame rate drops steadily the longer a world has been played, especially with mods or large redstone builds. Java Edition's default memory allocation is conservative and doesn't scale automatically with world size or mod count. Fix: Increase allocated RAM in your launcher's installation settings — 4–6 GB is a reasonable bump for modded or large worlds (don't over-allocate past your system's free RAM).