## Project Abandoned<\/p>\n
Long story short, the optimization approach still applies, but Forge\/NeoForge does not allow mod to modify EventBus.<\/p>\n
Unlike classes from Minecraft or Forge itself, EventBus is loaded not as part of the game, but as “library”, which makes it impossible to modify EventBus via Mixin or Transformer.<\/p>\n
In 1.2.0, in an effort of further improving performance, I used some dirty hack (or “non-standard approach” if you prefer) to modify the `ASMEventHandler` class, which is unfortunately broken in 1.18.2+. These releases are archived now, and are likely not receiving further update.<\/p>\n
## FastEvent<\/p>\n
is a Forge\/Neoforge optimization mod that optimizes one of the most fundamental systems in Forge: the Event system.<\/p>\n
## How Fast<\/p>\n
It’s not easy to make a test case for every supported Minecraft version, especially when the Event system for these versions are different from each other. So instead, I will provide a JMH benchmark report from a PR I made for Cleanroom project, in which I used the same optimization approach as FastEvent:<\/p>\n
### Register 10,000 event listeners, post event 0 times:<\/p>\n
“`
\nBenchmark Mode Cnt Score Error Units
\nBusPerformanceTest.register10000Legacy avgt 5 1126.498 \u00b1 284.633 ms\/op
\nBusPerformanceTest.register10000Modern avgt 5 1058.961 \u00b1 173.586 ms\/op
\n“`<\/p>\n
About 6.4% faster.<\/p>\n
### Register 1,000 event listeners, post event 10,000 times:<\/p>\n
“`
\nBenchmark Mode Cnt Score Error Units
\nBusPerformanceTest.register1000test10000Legacy avgt 5 4407.963 \u00b1 4250.643 ms\/op
\nBusPerformanceTest.register1000test10000Modern avgt 5 3550.578 \u00b1 1991.352 ms\/op
\n“`<\/p>\n
About 24% faster.<\/p>\n
### Original PR<\/p>\n
https:\/\/github.com\/CleanroomMC\/Cleanroom\/pull\/328#issuecomment-2801099504<\/p>\n
## How does it work<\/p>\n
(Nerdy technical details alert)<\/p>\n
When devs are using `@EventBusSubscriber` and\/or `@SubscribeEvent` to subscribe event handlers, the EventBus cannot get the event handler magically, instead only a `Method` object is available. So the most straight-forward approach is use this object directly: `method.invoke(…)`. This invocation will eventually be redirected by JVM back to the original method, allowing an event handler to receive an event after subscribing to it.<\/p>\n
But this (`method.invoke(…)`) is really slow. To make it faster, the EventBus will, at runtime, generate event handler classes for every method it found, eliminating expensive reflection based invocation.<\/p>\n
But generating classes introduces another slow-down. To make it even faster, FastEvent replaced class generation with lambda construction, speeding up event handler construction. Another benefit is that lambda is “hidden”, allowing JVM to perform more optimization.<\/p>\n
If you happen to know a bit Java, code examples below might be more intuitive for you:<\/p>\n
“`java
\nclass Listen {
\n public void onEvent(Event event) {
\n }
\n}
\nListen lis = new Listen();<\/p>\n
\/\/ EventBus will generate a new class for every event handler
\nclass IEventListener$Listen$onEvent implements IEventListener {
\n private Listen instance;
\n public IEventListener$Listen$onEvent(Listen instance) {
\n this.instance = instance;
\n }
\n @Override
\n public void invoke(Event event) {
\n instance.onEvent(event);
\n }
\n}
\nIEventListener handler = new IEventListener$Listen$onEvent(lis);<\/p>\n
\/\/ FastEvent uses lambda to generate event handler
\nIEventListener handler = lis::onEvent;
\n“`<\/p>\n","protected":false},"excerpt":{"rendered":"
speeding up the Event system in Forge\/NeoForge<\/p>\n","protected":false},"featured_media":69360,"template":"","meta":{"_minecraft_slug":"fastevent","_minecraft_project_id":"LauZQ6kM","_minecraft_author":"ZZZank","_minecraft_license":"MIT","_minecraft_downloads":1117164,"_minecraft_follows":30,"_minecraft_client_side":"optional","_minecraft_server_side":"optional","_minecraft_storage_type":"zip","_minecraft_archive_name":"fastevent.zip","_minecraft_size_bytes":381098,"_minecraft_version_count":12,"_minecraft_updated_at":"2026-05-16T12:41:55.995348Z","_minecraft_date_created":"2025-05-12T02:14:45.260296Z","_minecraft_date_modified":"2025-06-18T05:46:24.321394Z","_minecraft_project_url":"https:\/\/modrinth.com\/mod\/fastevent","_minecraft_icon_attachment_id":69360,"_minecraft_imported_at":"2026-06-03T22:53:03+00:00","_minecraft_import_hash":"34f9528354c9fdf49ebe9ebf7b3e952e","_minecraft_versions":"","_minecraft_links":"","_minecraft_gallery":"","_minecraft_api_metadata":""},"mod_category":[104,158,90],"mod_loader":[106,160],"minecraft_version":[48,53,56,36,37],"class_list":["post-69359","mod","type-mod","status-publish","has-post-thumbnail","hentry","mod_category-forge","mod_category-neoforge","mod_category-optimization","mod_loader-forge","mod_loader-neoforge","minecraft_version-1-16-5","minecraft_version-1-18-2","minecraft_version-1-19-2","minecraft_version-1-20-1","minecraft_version-1-21-1"],"yoast_head":"\n