diff --git a/.config/example.yml b/.config/example.yml
index ca47c31415..e23ab126c6 100644
--- a/.config/example.yml
+++ b/.config/example.yml
@@ -116,8 +116,12 @@ autoAdmin: true
 # Whether disable HSTS
 #disableHsts: true
 
-# Clustering
+# Number of worker processes
 #clusterLimit: 1
 
+# Job concurrency per worker
+# deliverJobConcurrency: 128;
+# inboxJobConcurrency: 16;
+
 # IP address family used for outgoing request (ipv4, ipv6 or dual)
 #outgoingAddressFamily: ipv4
diff --git a/src/boot/master.ts b/src/boot/master.ts
index b698548d47..381c4bc4ca 100644
--- a/src/boot/master.ts
+++ b/src/boot/master.ts
@@ -159,7 +159,7 @@ async function init(): Promise<Config> {
 	return config;
 }
 
-async function spawnWorkers(limit: number = Infinity) {
+async function spawnWorkers(limit: number = 1) {
 	const workers = Math.min(limit, os.cpus().length);
 	bootLogger.info(`Starting ${workers} worker${workers === 1 ? '' : 's'}...`);
 	await Promise.all([...Array(workers)].map(spawnWorker));
diff --git a/src/config/types.ts b/src/config/types.ts
index 9ecf495c42..18382d7435 100644
--- a/src/config/types.ts
+++ b/src/config/types.ts
@@ -42,6 +42,9 @@ export type Source = {
 	id: string;
 
 	outgoingAddressFamily?: 'ipv4' | 'ipv6' | 'dual';
+
+	deliverJobConcurrency?: number;
+	inboxJobConcurrency?: number;
 };
 
 /**
diff --git a/src/queue/index.ts b/src/queue/index.ts
index a7e9b9814f..0b20017291 100644
--- a/src/queue/index.ts
+++ b/src/queue/index.ts
@@ -203,8 +203,8 @@ export function createCleanRemoteFilesJob() {
 
 export default function() {
 	if (!program.onlyServer) {
-		deliverQueue.process(128, processDeliver);
-		inboxQueue.process(128, processInbox);
+		deliverQueue.process(config.deliverJobConcurrency || 128, processDeliver);
+		inboxQueue.process(config.inboxJobConcurrency || 16, processInbox);
 		processDb(dbQueue);
 		procesObjectStorage(objectStorageQueue);
 	}