diff --git a/object_schema.cpp b/object_schema.cpp
index adf5bc94..e4cbc195 100644
--- a/object_schema.cpp
+++ b/object_schema.cpp
@@ -22,7 +22,7 @@
 using namespace realm;
 using namespace std;
 
-ObjectSchema::ObjectSchema(realm::Group *group, std::string name) : name(name) {
+ObjectSchema::ObjectSchema(realm::Group *group, const std::string &name) : name(name) {
     TableRef table = ObjectStore::table_for_object_type(group, name);
     size_t count = table->get_column_count();
     for (size_t col = 0; col < count; col++) {
@@ -55,7 +55,7 @@ ObjectSchema::ObjectSchema(realm::Group *group, std::string name) : name(name) {
     }
 }
 
-Property *ObjectSchema::property_for_name(std::string name) {
+Property *ObjectSchema::property_for_name(const std::string &name) {
     for (auto& prop:properties) {
         if (prop.name == name) {
             return &prop;
diff --git a/object_schema.hpp b/object_schema.hpp
index 23918117..54ee2a14 100644
--- a/object_schema.hpp
+++ b/object_schema.hpp
@@ -29,13 +29,13 @@ namespace realm {
     class ObjectSchema {
     public:
         ObjectSchema() {}
-        ObjectSchema(Group *group, std::string name);
+        ObjectSchema(Group *group, const std::string &name);
 
         std::string name;
         std::vector<Property> properties;
         std::string primary_key;
 
-        Property *property_for_name(std::string name);
+        Property *property_for_name(const std::string &name);
         Property *primary_key_property() {
             return property_for_name(primary_key);
         }
diff --git a/object_store.cpp b/object_store.cpp
index fd20858a..b8021c33 100644
--- a/object_store.cpp
+++ b/object_store.cpp
@@ -109,14 +109,14 @@ void ObjectStore::set_primary_key_for_object(realm::Group *group, StringData obj
     }
 }
 
-string ObjectStore::object_type_for_table_name(string table_name) {
+string ObjectStore::object_type_for_table_name(const string &table_name) {
     if (table_name.compare(0, 6, c_object_table_name_prefix) == 0) {
         return table_name.substr(6, table_name.length()-6);
     }
     return string();
 }
 
-string ObjectStore::table_name_for_object_type(string object_type) {
+string ObjectStore::table_name_for_object_type(const string &object_type) {
     return c_object_table_name_prefix + object_type;
 }
 
@@ -124,7 +124,7 @@ realm::TableRef ObjectStore::table_for_object_type(realm::Group *group, StringDa
     return group->get_table(table_name_for_object_type(object_type));
 }
 
-realm::TableRef ObjectStore::table_for_object_type_create_if_needed(realm::Group *group, StringData object_type, bool &created) {
+realm::TableRef ObjectStore::table_for_object_type_create_if_needed(realm::Group *group, const StringData &object_type, bool &created) {
     return group->get_or_add_table(table_name_for_object_type(object_type), &created);
 }
 
diff --git a/object_store.hpp b/object_store.hpp
index f342d4a9..f067c605 100644
--- a/object_store.hpp
+++ b/object_store.hpp
@@ -83,9 +83,9 @@ namespace realm {
         // must be in write transaction to set
         static void set_primary_key_for_object(Group *group, StringData object_type, StringData primary_key);
 
-        static TableRef table_for_object_type_create_if_needed(Group *group, StringData object_type, bool &created);
-        static std::string table_name_for_object_type(std::string class_name);
-        static std::string object_type_for_table_name(std::string table_name);
+        static TableRef table_for_object_type_create_if_needed(Group *group, const StringData &object_type, bool &created);
+        static std::string table_name_for_object_type(const std::string &class_name);
+        static std::string object_type_for_table_name(const std::string &table_name);
 
         // returns if any indexes were changed
         static bool update_indexes(Group *group, Schema &schema);