perf: reduce message delivery latency across all connection scenarios

Surgical optimizations to eliminate message delivery delays after QR scan,
pm2 restart, and code updates:

Buffer/Flush:
- bufferTimeoutMs: 5s→3s (safety auto-flush cap)
- maxBufferTimeoutMs: 8s→3s (adaptive timeout ceiling)
- flushDebounceMs: 100ms→10ms (createBufferedFunction debounce)
- OFFLINE_BUFFER_TIMEOUT_MS: 5s→2s (first-connection buffer)
- AwaitingInitialSync: 4s→2s (history sync wait)

Mutex parallelism:
- receiptMutex: global→keyed by remoteJid (parallel receipt processing)
- notificationMutex: global→keyed by remoteJid (parallel notification processing)

Delay reduction:
- retryRequestDelayMs: 250ms→150ms
- transactionOpts.delayBetweenTriesMs: 3s→1s

Offline processing:
- BATCH_SIZE: 10→25 (fewer event loop yields)

Expected impact: QR scan worst-case 8s→2s, pm2 restart 100ms→10ms.
All existing customizations preserved (Circuit Breaker, Prometheus,
TcToken, CTWA Recovery, sanitizeCallerPn, Session Cleanup, LID Mapping,
Identity Key cache, clearRoutingInfoOnStart, wasm-bridge).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/Defaults/index.ts

@@ -67,7 +67,7 @@ export const DEFAULT_CONNECTION_CONFIG: SocketConfig = {
 	emitOwnEvents: true,
 	defaultQueryTimeoutMs: 30_000,
 	customUploadHosts: [],
-	retryRequestDelayMs: 250,
+	retryRequestDelayMs: 150,
 	maxMsgRetryCount: 5,
 	fireInitQueries: true,
 	auth: undefined as unknown as AuthenticationState,
@@ -78,7 +78,7 @@ export const DEFAULT_CONNECTION_CONFIG: SocketConfig = {
 	shouldSyncHistoryMessage: () => true,
 	shouldIgnoreJid: () => false,
 	linkPreviewImageThumbnailWidth: 192,
-	transactionOpts: { maxCommitRetries: 10, delayBetweenTriesMs: 3000 },
+	transactionOpts: { maxCommitRetries: 10, delayBetweenTriesMs: 1000 },
 	generateHighQualityLinkPreview: false,
 	enableAutoSessionRecreation: true,
 	enableRecentMessageCache: true,

src/Socket/chats.ts

@@ -102,14 +102,14 @@ export const makeChatsSocket = (config: SocketConfig) => {
 	/** this mutex ensures that messages from the same chat are processed in order, while allowing parallel processing of messages from different chats */
 	const messageMutex = makeKeyedMutex()
 
-	/** this mutex ensures that receipts are processed in order */
-	const receiptMutex = makeMutex()
+	/** this mutex ensures that receipts from the same chat are processed in order, while allowing parallel processing across chats */
+	const receiptMutex = makeKeyedMutex()
 
 	/** this mutex ensures that app state patches are processed in order */
 	const appStatePatchMutex = makeMutex()
 
-	/** this mutex ensures that notifications are processed in order */
-	const notificationMutex = makeMutex()
+	/** this mutex ensures that notifications from the same chat are processed in order, while allowing parallel processing across chats */
+	const notificationMutex = makeKeyedMutex()
 
 	// Timeout for AwaitingInitialSync state
 	let awaitingSyncTimeout: NodeJS.Timeout | undefined
@@ -1495,7 +1495,7 @@ export const makeChatsSocket = (config: SocketConfig) => {
 
 		awaitingSyncTimeout = setTimeout(() => {
 			if (syncState === SyncState.AwaitingInitialSync) {
-				logger.warn('Timeout in AwaitingInitialSync (4s), forcing state to Online and flushing buffer')
+				logger.warn('Timeout in AwaitingInitialSync (2s), forcing state to Online and flushing buffer')
 				syncState = SyncState.Online
 				ev.flush()
 
@@ -1505,7 +1505,7 @@ export const makeChatsSocket = (config: SocketConfig) => {
 				const accountSyncCounter = (authState.creds.accountSyncCounter || 0) + 1
 				ev.emit('creds.update', { accountSyncCounter })
 			}
-		}, 4_000)
+		}, 2_000)
 	})
 
 	// When an app state sync key arrives (myAppStateKeyId is set) and there are

src/Socket/messages-recv.ts

@@ -1282,7 +1282,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 
 		try {
 			await Promise.all([
-				receiptMutex.mutex(async () => {
+				receiptMutex.mutex(remoteJid || 'unknown', async () => {
 					const status = getStatusFromReceiptType(attrs.type)
 					if (
 						typeof status !== 'undefined' &&
@@ -1356,7 +1356,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 
 		try {
 			await Promise.all([
-				notificationMutex.mutex(async () => {
+				notificationMutex.mutex(remoteJid || 'unknown', async () => {
 					const msg = await processNotification(node)
 					if (msg) {
 						const fromMe = areJidsSameUser(node.attrs.participant || remoteJid, authState.creds.me!.id)
@@ -1985,7 +1985,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		let isProcessing = false
 
 		// Number of nodes to process before yielding to event loop
-		const BATCH_SIZE = 10
+		const BATCH_SIZE = 25
 
 		const enqueue = (type: MessageType, node: BinaryNode) => {
 			nodes.push({ type, node })

src/Socket/socket.ts

@@ -1668,7 +1668,7 @@ export const makeSocket = (config: SocketConfig) => {
 	// the offline buffer entirely so live messages are not held hostage waiting for the
 	// server to finish flushing the pending-message backlog (CB:ib,,offline).
 	// For normal restarts (no stale routingInfo) the standard 5 s safety cap applies.
-	const OFFLINE_BUFFER_TIMEOUT_MS = 5_000
+	const OFFLINE_BUFFER_TIMEOUT_MS = 2_000
 	let offlineBufferTimeout: NodeJS.Timeout | undefined
 
 	process.nextTick(() => {

src/Utils/event-buffer.ts

@@ -57,12 +57,12 @@ export function loadBufferConfig(): BufferConfig {
 		// perf(inbound-latency): reduced from 15s → 5s so the safety auto-flush fires sooner.
 		// processNodeWithBuffer always calls ev.flush() explicitly (no-op for this timer),
 		// but socket.ts's offline-phase buffer and any stalled buffer benefit from the lower cap.
-		bufferTimeoutMs: parseInt(process.env.BAILEYS_BUFFER_TIMEOUT_MS || '5000', 10),
+		bufferTimeoutMs: parseInt(process.env.BAILEYS_BUFFER_TIMEOUT_MS || '3000', 10),
 		minBufferTimeoutMs: parseInt(process.env.BAILEYS_BUFFER_MIN_TIMEOUT_MS || '1000', 10),
-		maxBufferTimeoutMs: parseInt(process.env.BAILEYS_BUFFER_MAX_TIMEOUT_MS || '8000', 10),
+		maxBufferTimeoutMs: parseInt(process.env.BAILEYS_BUFFER_MAX_TIMEOUT_MS || '3000', 10),
 		maxHistoryCacheSize: parseInt(process.env.BAILEYS_BUFFER_MAX_HISTORY_CACHE || '10000', 10),
 		maxBufferSize: parseInt(process.env.BAILEYS_BUFFER_MAX_SIZE || '5000', 10),
-		flushDebounceMs: parseInt(process.env.BAILEYS_BUFFER_FLUSH_DEBOUNCE_MS || '100', 10),
+		flushDebounceMs: parseInt(process.env.BAILEYS_BUFFER_FLUSH_DEBOUNCE_MS || '10', 10),
 		enableAdaptiveTimeout: process.env.BAILEYS_BUFFER_ADAPTIVE_TIMEOUT !== 'false',
 		enableMetrics: process.env.BAILEYS_BUFFER_METRICS === 'true' || process.env.BAILEYS_PROMETHEUS_ENABLED === 'true',
 		lruCleanupRatio: parseFloat(process.env.BAILEYS_BUFFER_LRU_CLEANUP_RATIO || '0.2'),