diff --git a/lib/rdoc/code_object/context.rb b/lib/rdoc/code_object/context.rb
index ccc9203141..da85909742 100644
--- a/lib/rdoc/code_object/context.rb
+++ b/lib/rdoc/code_object/context.rb
@@ -186,8 +186,8 @@ def add(klass, name, comment)
   def add_alias(an_alias)
     return an_alias unless @document_self
 
-    method_attr = find_method(an_alias.old_name, an_alias.singleton) ||
-                  find_attribute(an_alias.old_name, an_alias.singleton)
+    method_attr = find_method_from_hash(an_alias.old_name, an_alias.singleton) ||
+                  find_attribute_from_hash(an_alias.old_name, an_alias.singleton)
 
     if method_attr
       method_attr.add_alias an_alias, self
@@ -749,6 +749,14 @@ def find_attribute(name, singleton)
     @attributes.find { |a| a.name == name && a.singleton == singleton }
   end
 
+  def find_attribute_from_hash(name, singleton) # :nodoc:
+    name = name.delete_suffix('=')
+    key = "#{singleton ? '::' : '#'}#{name}"
+    attribute = @methods_hash[key]
+    attribute = @methods_hash["#{key}="] unless RDoc::Attr === attribute
+    attribute if RDoc::Attr === attribute && attribute.singleton == singleton
+  end
+
   ##
   # Finds an attribute with +name+ in this context
 
@@ -843,6 +851,12 @@ def find_method(name, singleton)
     }
   end
 
+  def find_method_from_hash(name, singleton) # :nodoc:
+    method = @methods_hash["#{singleton ? '::' : '#'}#{name}"]
+    # ponytail: keep the fallback until incremental rebuilds make this hash canonical.
+    RDoc::Attr === method ? find_method(name, singleton) : method
+  end
+
   ##
   # Finds a instance or module method with +name+ in this context
 
diff --git a/lib/rdoc/parser/rbs.rb b/lib/rdoc/parser/rbs.rb
index 107e6d0219..ff3b68a43b 100644
--- a/lib/rdoc/parser/rbs.rb
+++ b/lib/rdoc/parser/rbs.rb
@@ -95,7 +95,7 @@ def merge_attribute_methods(context, name, rw, singleton, comment, type_signatur
     method_names << name if rw.include?('R')
     method_names << "#{name}=" if rw.include?('W')
 
-    methods = method_names.map { |method_name| context.find_method(method_name, singleton) }
+    methods = method_names.map { |method_name| context.find_method_from_hash(method_name, singleton) }
     methods.compact.each do |method|
       merge_documentation method, comment, type_signature_lines
     end
@@ -135,7 +135,7 @@ def parse_attr_decl(decl, context)
     type_signature_lines = [decl.type.to_s]
     name = decl.name.to_s
     singleton = decl.kind == :singleton
-    if attribute = context.find_attribute(name, singleton)
+    if attribute = context.find_attribute_from_hash(name, singleton)
       merge_documentation attribute, comment, type_signature_lines if
         attr_rw_matches? attribute.rw, rw
       return
@@ -245,7 +245,7 @@ def parse_method_decl(decl, context)
     singleton = rdoc_method_singleton?(decl)
     visibility = rdoc_method_visibility(decl)
 
-    if method = context.find_method(method_name, singleton)
+    if method = context.find_method_from_hash(method_name, singleton)
       merge_documentation method, comment, type_signature_lines
       return
     end
diff --git a/test/rdoc/parser/rbs_test.rb b/test/rdoc/parser/rbs_test.rb
index 0365462cc1..7b22d26255 100644
--- a/test/rdoc/parser/rbs_test.rb
+++ b/test/rdoc/parser/rbs_test.rb
@@ -143,6 +143,48 @@ def greet: () -> String
     assert_equal ['() -> String'], greet.type_signature_lines
   end
 
+  def test_scan_finds_existing_method_after_store_index_rebuild
+    ruby_top_level = @store.add_file 'sample.rb'
+    sample = ruby_top_level.add_class RDoc::NormalClass, 'Sample'
+
+    name = RDoc::AnyMethod.new 'name'
+    name.record_location ruby_top_level
+    sample.add_method name
+
+    name_writer = RDoc::Attr.new 'name', 'W', nil
+    name_writer.record_location ruby_top_level
+    sample.add_attribute name_writer
+
+    util_parser("class Sample\nend\n").scan
+    @store.clear_file_contributions @filename, keep_position: true
+    util_parser(<<~RBS).scan
+      class Sample
+        def name: () -> String
+      end
+    RBS
+
+    assert_equal ['() -> String'], name.type_signature_lines
+  end
+
+  def test_scan_indexes_forward_attribute_alias
+    util_parser(<<~RBS).scan
+      class Sample
+        alias display_name name
+
+        # Base attribute docs.
+        attr_reader name: String
+
+        # Dedicated attribute docs.
+        attr_reader display_name: String
+      end
+    RBS
+
+    sample = @store.find_class_named 'Sample'
+    display_name = sample.find_attribute 'display_name', false
+
+    assert_equal "Base attribute docs.\n---\nDedicated attribute docs.", display_name.comment.to_s.strip
+  end
+
   def test_scan_preserves_rbs_markdown_when_extending_method_documentation
     ruby_top_level = @store.add_file 'sample.rb'
     sample = ruby_top_level.add_class RDoc::NormalClass, 'Sample'
@@ -266,6 +308,13 @@ class PrivateSample
     assert_equal :public, private_constructor.visibility
   end
 
+  def test_scan_member_lookup_linear_performance
+    assert_linear_performance([1, 10, 100]) do |factor|
+      members = Array.new(factor * 200) { |i| "  def m#{i}: () -> void\n  attr_reader a#{i}: String" }.join("\n")
+      util_parser("class C\n#{members}\nend\n").scan
+    end
+  end
+
   def util_parser(content)
     RDoc::Parser::RBS.new @top_level, content, @options, @stats
   end
diff --git a/test/rdoc/parser/ruby_test.rb b/test/rdoc/parser/ruby_test.rb
index 40cc6f4893..2020f9f715 100644
--- a/test/rdoc/parser/ruby_test.rb
+++ b/test/rdoc/parser/ruby_test.rb
@@ -2722,6 +2722,13 @@ def test_read_directive_linear_performance
     end
   end
 
+  def test_alias_lookup_linear_performance
+    assert_linear_performance([1, 10, 100]) do |factor|
+      methods = Array.new(factor * 100) { |i| "  def m#{i}; end\n  alias a#{i} m#{i}" }.join("\n")
+      util_parser "class C#{factor}\n#{methods}\nend\n"
+    end
+  end
+
   def test_code_object_token_stream
     util_parser <<~RUBY
       class Foo
diff --git a/test/rdoc/rdoc_context_test.rb b/test/rdoc/rdoc_context_test.rb
index d193b324cd..ae54651f30 100644
--- a/test/rdoc/rdoc_context_test.rb
+++ b/test/rdoc/rdoc_context_test.rb
@@ -541,6 +541,16 @@ def test_find_attribute_named
     assert_equal 'RW', @c1.find_attribute_named('attr_accessor').rw
   end
 
+  def test_find_attribute_from_hash
+    singleton = RDoc::Attr.new 'singleton', 'R', nil, singleton: true
+    @context.add_attribute singleton
+
+    assert_same @c1.find_attribute_named('attr_reader'), @c1.find_attribute_from_hash('attr_reader', false)
+    assert_same @c1.find_attribute_named('attr_writer'), @c1.find_attribute_from_hash('attr_writer=', false)
+    assert_same singleton, @context.find_attribute_from_hash('singleton', true)
+    assert_nil @c1.find_attribute_from_hash('attr_reader', true)
+  end
+
   def test_find_class_method_named
     assert_nil @c1.find_class_method_named('none')
 
@@ -584,6 +594,16 @@ def test_find_method
     assert_equal @c2_b, loaded_c2.find_method('b', nil)
   end
 
+  def test_find_method_from_hash
+    instance = RDoc::AnyMethod.new 'instance', singleton: nil
+    @context.add_method instance
+
+    assert_same instance, @context.find_method_from_hash('instance', false)
+    assert_same instance, @context.find_method_from_hash('instance', nil)
+    assert_same @c1__m, @c1.find_method_from_hash('m', true)
+    assert_nil @c1.find_method_from_hash('attr', false)
+  end
+
   def test_find_method_named
     assert_equal true, @c1.find_method_named('m').singleton
   end