Refactors event, entity, and physics management to use thread-safe and lock-free data structures (Immutable collections, ConcurrentQueue, ConcurrentDictionary, Channel) for improved concurrency and performance. Replaces O(n) queue lookups with O(1) set/dictionary checks, ensures atomic updates for shared state, and optimizes queue draining and deferred action processing. Updates related code to use new APIs and patterns, and adds documentation for thread safety and workflow.
Replaces direct increments of LastClientListUpdateID with a thread-safe IncrementLastClientListUpdateID method and uses Interlocked for atomic operations. Refactors EntitySpawner to lock access to the spawn/remove queue for thread safety. Updates INetSerializableStruct to use concurrent collections for cached variables and type behaviors, improving thread safety in networking code.
