ThreadTweak Guide: Tuning Game, Bootstrap, Main, IO, and Integrated Server Threads

ThreadTweak lets you adjust the thread counts and priorities Minecraft uses for its main work, and this guide covers the priority options for the Game, Bootstrap, Main, IO, and Integrated Server threads plus the two worker count settings.

What the settings control

The mod exposes two worker thread counts and five priority settings. The counts decide how many worker threads are spun up for a given phase, while the priorities decide how much processor attention each thread category receives relative to everything else running on your machine.

• Bootstrap Worker Thread Count — the number of worker threads used during the bootstrap phase.
• Main Worker Thread Count — the number of worker threads used for the main workload.
• Game Thread Priority — the priority of the game thread.
• Bootstrap Worker Priority — the priority of the bootstrap worker threads.
• Main Worker Priority — the priority of the main worker threads.
• IO Worker Priority — the priority of the IO worker threads.
• integratedServer — the priority of the Integrated Server thread.

Bootstrap Worker Thread Count

This setting controls how many worker threads are dedicated to the bootstrap phase. The tooltip attached to it carries a clear warning: raising this value is known to decrease performance. Treat the default as the safe choice, and only lower it if you have a specific reason and are prepared to test the result.

Main Worker Thread Count

This is the count of worker threads handling the main workload. Its tooltip notes two things. First, the value greatly affects load times, so this is one of the more noticeable settings to change. Second, it may also affect in-game performance, meaning the effect is not limited to startup. Because both load times and gameplay can shift, change this value in small steps and compare results rather than making a large jump.

Priority settings

Five separate priorities are available, one for each thread category:

• Game Thread Priority for the game thread.
• Bootstrap Worker Priority for the bootstrap workers.
• Main Worker Priority for the main workers.
• IO Worker Priority for the IO workers.
• integratedServer for the Integrated Server thread.

Each priority raises or lowers how the operating system schedules that category of thread. Giving a category more priority means it gets serviced ahead of lower-priority work; giving it less means it yields to other threads. There is no single correct arrangement, because the right balance depends on your hardware and what else is running. If the Integrated Server is struggling while the game thread is fine, for example, the integratedServer priority is the relevant control.

How to operate the settings

Open the mod's interface to reach these options. Each setting is adjusted through its own control in that interface, and changes take effect according to how the mod applies them. For any action that is bound to a hotkey rather than a control in the interface, use the corresponding hotkey and set it in the controls menu — no default key is assumed here.

Tuning advice

• Start from the defaults and change one setting at a time so you can tell what caused any difference.
• Be cautious with Bootstrap Worker Thread Count; the tooltip states that increasing it is known to decrease performance.
• Expect Main Worker Thread Count to matter most for load times, with possible effects on in-game performance as well.
• Use the priority settings to shift scheduling weight between categories rather than as a blanket "higher is better" fix.
• Revert a change if it does not help, and keep notes on what you tried so you can reproduce a good result.