diff --git a/js4g/StackMachine.cc b/js4g/StackMachine.cc
index 14ae3c5..e699c72 100644
--- a/js4g/StackMachine.cc
+++ b/js4g/StackMachine.cc
@@ -277,7 +277,7 @@ namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 int
 main()
 {
-	std::deque< std::string > program;
+	std::vector< std::string > program;
 
 	while( std::cin )
 	{
diff --git a/js4g/StackMachine.h b/js4g/StackMachine.h
index 8036000..b852604 100644
--- a/js4g/StackMachine.h
+++ b/js4g/StackMachine.h
@@ -12,6 +12,9 @@ static_assert( __cplusplus >= 2023'02 );
 #include <string>
 #include <variant>
 #include <deque>
+#include <list>
+
+#include <boost/container/flat_map.hpp>
 
 namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 {
@@ -36,20 +39,26 @@ namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 			// It grows on the "back".
 			// A `std::deque` is used instead of `std::vector`, because
 			// it helps cut down on large allocations, by subdividing things.
-			std::deque< std::variant< std::string, Integer > > stack;
+			std::vector< std::variant< std::string, Integer > > stack;
 
 			// TODO: Should these tokens be binary?
 			// Upside: compressed.
 			// Downside: more memory management in the machine end?
-			std::deque< std::string > tokens;
+
+			// It's `void *` to break the cycle with itself
+			struct TokenHolder;
+			//using Token= std::variant< std::string, TokenHolder * >;
+			using Token= std::string;
+
+			std::vector< std::string > tokens;
 
 			struct Tokenizer
 			{
-				std::deque< std::string >::const_iterator pos;
-				std::deque< std::string >::const_iterator end;
+				std::vector< Token >::const_iterator pos;
+				std::vector< Token >::const_iterator end;
 
 				explicit
-				Tokenizer( const std::deque< std::string > &tokens )
+				Tokenizer( const std::vector< Token > &tokens )
 					: pos( tokens.begin() ), end( tokens.end() ) {}
 
 				bool hasNext() const { return pos != end; }
@@ -60,8 +69,8 @@ namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 			std::vector< Tokenizer > tokenStack;
 
 
-			std::deque< std::string > wordNames;
-			std::unordered_map< std::string_view, std::deque< std::string > > words;
+			std::list< std::string > wordNames;
+			std::unordered_map< std::string_view, std::vector< std::string > > words;
 
 			// Which side of the current conditional to take.
 			enum ConditionalState { If, Else, Skipped };
@@ -78,7 +87,7 @@ namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 			void runWord( std::string_view word );
 
 			std::variant< std::string, Integer > pop();
-			const std::variant< std::string, Integer > &peek();
+			std::variant< std::string, Integer > &peek();
 
 			void push( std::string s );
 			void push( Integer s );
@@ -99,7 +108,7 @@ namespace Dillo::Hydrogen::JavaScriptForge	::detail::  StackMachine_m
 			StackMachine( std::ostream &output= std::cout );
 
 			void
-			loadProgram( std::deque< std::string > tokens )
+			loadProgram( std::vector< std::string > tokens )
 			{
 				this->tokens= std::move( tokens );
 				tokenStack.clear();