Only Sync if told to do so

src/github.com/matrix-org/go-neb/clients/clients.go

@@ -219,7 +219,9 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 		})
 	}
 
+	if config.Sync {
 		go client.Sync()
+	}
 
 	return client, nil
 }