No multithreading for now

sw/src/userspace/remotectl.cpp

@@ -1832,11 +1832,14 @@ int run_remote_control_server(
     acq_server.start_server();
     timetagger_server.start_server();
 
+    // We could start a few background threads, each calling io.run().
+    // It may improve performance a little bit.
+    // However, if there are synchronization bugs, it would cause weird issues
+    // that are difficult to track down. So let's keep just one thread for now.
+
     log(LOG_INFO, "Running, press Ctrl-C to stop");
     io.run();
 
-    // TODO -- multi-threading
-
     return command_handler.exit_status();
 }