diff --git a/lib/jsonapi/basic_resource.rb b/lib/jsonapi/basic_resource.rb
index da9042658..ea8b19ea7 100644
--- a/lib/jsonapi/basic_resource.rb
+++ b/lib/jsonapi/basic_resource.rb
@@ -453,6 +453,9 @@ def inherited(subclass)
 
         subclass._routed = false
         subclass._warned_missing_route = false
+
+        subclass._clear_cached_attribute_options
+        subclass._clear_fields_cache
       end
 
       def rebuild_relationships(relationships)
@@ -527,6 +530,9 @@ def attributes(*attrs)
       end
 
       def attribute(attribute_name, options = {})
+        _clear_cached_attribute_options
+        _clear_fields_cache
+
         attr = attribute_name.to_sym
 
         check_reserved_attribute_name(attr)
@@ -693,7 +699,7 @@ def sortable_field?(key, context = nil)
       end
 
       def fields
-        _relationships.keys | _attributes.keys
+        @_fields_cache ||= _relationships.keys | _attributes.keys
       end
 
       def resources_for(records, context)
@@ -826,7 +832,7 @@ def verify_relationship_filter(filter, raw, _context = nil)
 
       # quasi private class methods
       def _attribute_options(attr)
-        default_attribute_options.merge(@_attributes[attr])
+        @_cached_attribute_options[attr] ||= default_attribute_options.merge(@_attributes[attr])
       end
 
       def _attribute_delegated_name(attr)
@@ -1063,6 +1069,8 @@ def construct_order_options(sort_params)
       end
 
       def _add_relationship(klass, *attrs)
+        _clear_fields_cache
+
         options = attrs.extract_options!
         options[:parent_resource] = self
 
@@ -1107,6 +1115,14 @@ def register_relationship(name, relationship_object)
         @_relationships[name] = relationship_object
       end
 
+      def _clear_cached_attribute_options
+        @_cached_attribute_options = {}
+      end
+
+      def _clear_fields_cache
+        @_fields_cache = nil
+      end
+
       private
 
       def check_reserved_resource_name(type, name)
diff --git a/lib/jsonapi/link_builder.rb b/lib/jsonapi/link_builder.rb
index 99cd6223c..6ede8a022 100644
--- a/lib/jsonapi/link_builder.rb
+++ b/lib/jsonapi/link_builder.rb
@@ -123,16 +123,16 @@ def module_scopes_from_class(klass)
     end
 
     def resources_path(source_klass)
-      formatted_module_path_from_class(source_klass) + format_route(source_klass._type.to_s)
+      @_resources_path ||= {}
+      @_resources_path[source_klass] ||= formatted_module_path_from_class(source_klass) + format_route(source_klass._type.to_s)
     end
 
     def resource_path(source)
-      url = "#{resources_path(source.class)}"
-
-      unless source.class.singleton?
-        url = "#{url}/#{source.id}"
+      if source.class.singleton?
+        resources_path(source.class)
+      else
+        "#{resources_path(source.class)}/#{source.id}"
       end
-      url
     end
 
     def resource_url(source)
diff --git a/lib/jsonapi/resource_serializer.rb b/lib/jsonapi/resource_serializer.rb
index e5749a98e..5751adb67 100644
--- a/lib/jsonapi/resource_serializer.rb
+++ b/lib/jsonapi/resource_serializer.rb
@@ -230,7 +230,7 @@ def attributes_hash(source, fetchable_fields)
     end
 
     def custom_generation_options
-      {
+      @_custom_generation_options ||= {
         serializer: self,
         serialization_options: @serialization_options
       }