Index: src/ResolvExpr/RenameVars.cc
===================================================================
--- src/ResolvExpr/RenameVars.cc	(revision c66254e1a876dbcd46b647136bf10d44b9645140)
+++ src/ResolvExpr/RenameVars.cc	(revision 16907789400504da4a690ba2030d00525e23c030)
@@ -10,6 +10,6 @@
 // Created On       : Sun May 17 12:05:18 2015
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Wed Mar  2 17:36:32 2016
-// Update Count     : 5
+// Last Modified On : Tue Apr 30 17:07:57 2019
+// Update Count     : 7
 //
 
@@ -39,5 +39,5 @@
 		  private:
 			int level, resetCount;
-			std::list< std::map< std::string, std::string > > mapStack;
+			std::list< std::unordered_map< std::string, std::string > > mapStack;
 		};
 
@@ -55,5 +55,5 @@
 	namespace {
 		RenameVars::RenameVars() : level( 0 ), resetCount( 0 ) {
-			mapStack.push_front( std::map< std::string, std::string >() );
+			mapStack.push_front( std::unordered_map< std::string, std::string >() );
 		}
 
@@ -65,5 +65,5 @@
 		void RenameVars::previsit( TypeInstType * instType ) {
 			previsit( (Type *)instType );
-			std::map< std::string, std::string >::const_iterator i = mapStack.front().find( instType->name );
+			std::unordered_map< std::string, std::string >::const_iterator i = mapStack.front().find( instType->name );
 			if ( i != mapStack.front().end() ) {
 				instType->name = i->second;
Index: src/ResolvExpr/TypeEnvironment.h
===================================================================
--- src/ResolvExpr/TypeEnvironment.h	(revision c66254e1a876dbcd46b647136bf10d44b9645140)
+++ src/ResolvExpr/TypeEnvironment.h	(revision 16907789400504da4a690ba2030d00525e23c030)
@@ -9,7 +9,7 @@
 // Author           : Richard C. Bilson
 // Created On       : Sun May 17 12:24:58 2015
-// Last Modified By : Aaron B. Moss
-// Last Modified On : Mon Jun 18 11:58:00 2018
-// Update Count     : 4
+// Last Modified By : Peter A. Buhr
+// Last Modified On : Tue Apr 30 23:04:10 2019
+// Update Count     : 9
 //
 
@@ -18,6 +18,7 @@
 #include <iostream>                    // for ostream
 #include <list>                        // for list, list<>::iterator, list<>...
-#include <map>                         // for map, map<>::value_compare
-#include <set>                         // for set
+#include <map>						   // for map, map<>::value_compare
+#include <unordered_map>
+#include <set>						   // for set
 #include <string>                      // for string
 #include <utility>                     // for move, swap
@@ -64,6 +65,6 @@
 		AssertionSetValue() : isUsed(false), resnSlot(0) {}
 	};
-	typedef std::map< DeclarationWithType*, AssertionSetValue, AssertCompare > AssertionSet;
-	typedef std::map< std::string, TypeDecl::Data > OpenVarSet;
+	typedef std::map< DeclarationWithType *, AssertionSetValue, AssertCompare > AssertionSet;
+	typedef std::unordered_map< std::string, TypeDecl::Data > OpenVarSet;
 
 	/// merges one set of open vars into another
Index: src/SynTree/Declaration.h
===================================================================
--- src/SynTree/Declaration.h	(revision c66254e1a876dbcd46b647136bf10d44b9645140)
+++ src/SynTree/Declaration.h	(revision 16907789400504da4a690ba2030d00525e23c030)
@@ -10,6 +10,6 @@
 // Created On       : Mon May 18 07:44:20 2015
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Sun Sep  3 19:24:06 2017
-// Update Count     : 131
+// Last Modified On : Wed May  1 07:46:49 2019
+// Update Count     : 134
 //
 
@@ -19,4 +19,5 @@
 #include <iosfwd>                // for ostream
 #include <list>                  // for list
+#include <unordered_map>         // for unordered_map
 #include <string>                // for string, operator+, allocator, to_string
 
@@ -334,5 +335,5 @@
 	virtual Declaration *acceptMutator( Mutator &m )  override { return m.mutate( this ); }
   private:
-	std::map< std::string, long long int > enumValues;
+	std::unordered_map< std::string, long long int > enumValues;
 	virtual std::string typeString() const override;
 };
Index: src/SynTree/TypeSubstitution.h
===================================================================
--- src/SynTree/TypeSubstitution.h	(revision c66254e1a876dbcd46b647136bf10d44b9645140)
+++ src/SynTree/TypeSubstitution.h	(revision 16907789400504da4a690ba2030d00525e23c030)
@@ -10,6 +10,6 @@
 // Created On       : Mon May 18 07:44:20 2015
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Sat Jul 22 09:52:24 2017
-// Update Count     : 3
+// Last Modified On : Tue Apr 30 22:52:47 2019
+// Update Count     : 9
 //
 
@@ -19,6 +19,6 @@
 #include <iosfwd>                  // for ostream
 #include <list>                    // for list<>::iterator, _List_iterator
-#include <map>                     // for _Rb_tree_iterator, map, map<>::val...
-#include <set>                     // for set
+#include <unordered_map>
+#include <unordered_set>
 #include <string>                  // for string, operator!=
 #include <utility>                 // for pair
@@ -78,6 +78,6 @@
 	friend class PassVisitor;
 
-	typedef std::map< std::string, Type* > TypeEnvType;
-	typedef std::map< std::string, Expression* > VarEnvType;
+	typedef std::unordered_map< std::string, Type * > TypeEnvType;
+	typedef std::unordered_map< std::string, Expression * > VarEnvType;
 	TypeEnvType typeEnv;
 	VarEnvType varEnv;
@@ -98,6 +98,6 @@
 	ActualIterator actualIt = actualBegin;
 	for ( ; formalIt != formalEnd; ++formalIt, ++actualIt ) {
-		if ( TypeDecl *formal = dynamic_cast< TypeDecl* >( *formalIt ) ) {
-			if ( TypeExpr *actual = dynamic_cast< TypeExpr* >( *actualIt ) ) {
+		if ( TypeDecl *formal = dynamic_cast< TypeDecl * >( *formalIt ) ) {
+			if ( TypeExpr *actual = dynamic_cast< TypeExpr * >( *actualIt ) ) {
 				if ( formal->get_name() != "" ) {
 					TypeEnvType::iterator i = typeEnv.find( formal->get_name() );
@@ -146,5 +146,5 @@
 		int subCount = 0;
 		bool freeOnly;
-		typedef std::set< std::string > BoundVarsType;
+		typedef std::unordered_set< std::string > BoundVarsType;
 		BoundVarsType boundVars;
 };