diff --git a/src/console_cmds.cpp b/src/console_cmds.cpp
index a5869f2b21..750fa768d3 100644
--- a/src/console_cmds.cpp
+++ b/src/console_cmds.cpp
@@ -3068,6 +3068,39 @@ DEF_CONSOLE_CMD(ConMiscDebug)
 	return true;
 }
 
+DEF_CONSOLE_CMD(ConSetNewGRFOptimiserFlags)
+{
+	if (argc < 1 || argc > 2) {
+		IConsoleHelp("Debug: misc set_newgrf_optimiser_flags.  Usage: 'set_newgrf_optimiser_flags [<flags>]'");
+		return true;
+	}
+
+	if (argc == 1) {
+		IConsolePrintF(CC_DEFAULT, "NewGRF optimiser flags: %X", _settings_game.debug.newgrf_optimiser_flags);
+	} else {
+		if (_game_mode == GM_MENU || (_networking && !_network_server)) {
+			IConsoleError("This command is only available in-game and in the editor, and not as a network client.");
+			return true;
+		}
+		extern uint NetworkClientCount();
+		if (_networking && NetworkClientCount() > 1) {
+			IConsoleError("This command is not available when network clients are connected.");
+			return true;
+		}
+
+		uint value = strtoul(argv[1], nullptr, 16);
+		if (_settings_game.debug.newgrf_optimiser_flags == value) return true;
+		_settings_game.debug.newgrf_optimiser_flags = value;
+
+		ReloadNewGRFData();
+
+		extern void PostCheckNewGRFLoadWarnings();
+		PostCheckNewGRFLoadWarnings();
+	}
+
+	return true;
+}
+
 DEF_CONSOLE_CMD(ConDoDisaster)
 {
 	if (argc == 0) {
@@ -3662,6 +3695,7 @@ void IConsoleStdLibRegister()
 	IConsole::CmdRegister("csleep",                  ConCSleep,           nullptr, true);
 	IConsole::CmdRegister("recalculate_road_cached_one_way_states", ConRecalculateRoadCachedOneWayStates, ConHookNoNetwork, true);
 	IConsole::CmdRegister("misc_debug",              ConMiscDebug,        nullptr, true);
+	IConsole::CmdRegister("set_newgrf_optimiser_flags", ConSetNewGRFOptimiserFlags, nullptr, true);
 
 	/* NewGRF development stuff */
 	IConsole::CmdRegister("reload_newgrfs",          ConNewGRFReload,     ConHookNewGRFDeveloperTool);
diff --git a/src/network/network.cpp b/src/network/network.cpp
index ddf3a3a13e..51c8ec3047 100644
--- a/src/network/network.cpp
+++ b/src/network/network.cpp
@@ -158,6 +158,10 @@ byte NetworkSpectatorCount()
 	return count;
 }
 
+uint NetworkClientCount() {
+	return (uint)NetworkClientInfo::GetNumItems();
+}
+
 /**
  * Change the company password of a given company.
  * @param company_id ID of the company the password should be changed for.
diff --git a/src/network/network_func.h b/src/network/network_func.h
index 88a5456a87..3096bbc1a9 100644
--- a/src/network/network_func.h
+++ b/src/network/network_func.h
@@ -37,6 +37,7 @@ extern StringList _network_host_list;
 extern StringList _network_ban_list;
 
 byte NetworkSpectatorCount();
+uint NetworkClientCount();
 bool NetworkIsValidClientName(const std::string_view client_name);
 bool NetworkValidateOurClientName();
 bool NetworkValidateClientName(std::string &client_name);