diff --git a/CHANGELOG.md b/CHANGELOG.md
index 088dce3..5e01e37 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,24 @@
 # Changelog
 
+## v1.0.0 - May 2026
+
+### Breaking changes
+
+- **Default trackables narrowed to embedded relations only.** Including
+  `Mongoid::RelationsDirtyTracking` now tracks `embeds_one` and `embeds_many`
+  relations only. Tracking `has_one`, `has_many`, `has_and_belongs_to_many`,
+  and `belongs_to` requires opt-in via `relations_dirty_tracking track_referenced: true`.
+  This is a performance change — tracking referenced relations forces them to be
+  loaded on every `after_initialize` and `after_save` callback. See the
+  [Upgrading from 0.x](README.md#upgrading-from-0x) section of the README.
+
+### Features
+
+- Add `:track_referenced` option to `relations_dirty_tracking` to re-enable
+  tracking of referenced relations on a per-class basis.
+- Expose `EMBEDDED_TRACKABLES` and `REFERENCED_TRACKABLES` constants for
+  applications that need to introspect or override the trackable set.
+
 ## v0.3.0 - May 2025
 
 - Support Mongoid 8.0, 8.1, and 9.0 (drop support for earlier versions)
diff --git a/README.md b/README.md
index 5a7c224..b43cbd4 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ class SampleDocument
   include Mongoid::RelationsDirtyTracking
 
   embeds_one  :foo
-  has_many    :bars
+  embeds_many :bars
 
   field :title, type: String
 end
@@ -39,9 +39,9 @@ doc.bars << Bar.new(title: 'bar')
 doc.title = 'New title'
 
 doc.relations_changed?      # => true
-doc.relation_changes        # => {"foo" => [nil, {"_id"=>"524c35ad1ac1c23084000040", "title" => "foo"}], "bars" => [nil, [{"_id"=>"524c35ad1ac1c23084000083"}]]}
+doc.relation_changes        # => {"foo" => [nil, {"_id"=>"524c35ad1ac1c23084000040", "title" => "foo"}], "bars" => [[], [{"_id"=>"524c35ad1ac1c23084000083", "title"=>"bar"}]]}
 doc.changed_with_relations? # => true
-doc.changes_with_relations  # => {"title" => [nil, "New title"], "foo" => [nil, {"_id"=>"524c35ad1ac1c23084000040", "title" => "foo"}], "bars" => [nil, [{"_id"=>"524c35ad1ac1c23084000083"}]]}
+doc.changes_with_relations  # => {"title" => [nil, "New title"], "foo" => [nil, {"_id"=>"524c35ad1ac1c23084000040", "title" => "foo"}], "bars" => [[], [{"_id"=>"524c35ad1ac1c23084000083", "title"=>"bar"}]]}
 
 doc.save
 doc.relations_changed?      # => false
@@ -50,6 +50,33 @@ doc.changed_with_relations? # => false
 doc.changes_with_relations  # => {}
 ```
 
+By default only **embedded** relations (`embeds_one`, `embeds_many`) are
+tracked. To also track referenced relations (`has_one`, `has_many`,
+`has_and_belongs_to_many`, `belongs_to`), opt in per class:
+
+```ruby
+class SampleDocument
+  include Mongoid::Document
+  include Mongoid::RelationsDirtyTracking
+
+  embeds_many :tags
+  has_many    :comments
+  belongs_to  :author
+
+  relations_dirty_tracking track_referenced: true
+end
+```
+
+You can still narrow tracking further with `:only` and `:except`. These
+filters are applied **within** the set of trackable relations selected by
+`:track_referenced`:
+
+```ruby
+relations_dirty_tracking only: %i[tags]                            # embedded only, only :tags
+relations_dirty_tracking only: %i[tags comments], track_referenced: true
+relations_dirty_tracking except: %i[tags], track_referenced: true  # everything except :tags
+```
+
 ## Disablement
 
 Relations dirty tracking can be resource intensive,
@@ -91,6 +118,84 @@ Mongoid::RelationsDirtyTracking.disable do
 end
 ```
 
+## Upgrading from 0.x
+
+**v1.0.0 narrowed the default trackables to embedded relations only.** Earlier
+versions tracked every kind of relation (embedded, has_one, has_many, HABTM,
+belongs_to) by default. We changed the default because tracking referenced
+relations forces those associations to be loaded on every `after_initialize`
+and `after_save` callback — a significant cost when documents are read in bulk
+or via background jobs.
+
+### How to tell if you are affected
+
+You are affected if any class in your application includes
+`Mongoid::RelationsDirtyTracking` **and** relies on dirty tracking for
+`has_one`, `has_many`, `has_and_belongs_to_many`, or `belongs_to` associations.
+A class is *not* affected if it only uses dirty tracking for `embeds_one` /
+`embeds_many` associations.
+
+A quick way to audit your codebase:
+
+```bash
+grep -rln "include Mongoid::RelationsDirtyTracking" app/ lib/
+```
+
+For each match, check whether the class actually consumes `relation_changes` /
+`changes_with_relations` / `relations_changed?` for a referenced relation
+(typically read by audit logs, `mongoid-history` callbacks, push-sync hooks,
+etc.).
+
+### Restoring the v0.x behaviour
+
+If you were depending on referenced relation tracking, add
+`track_referenced: true` to the macro call:
+
+```ruby
+# Before (v0.x — tracked everything by default)
+class Order
+  include Mongoid::Document
+  include Mongoid::RelationsDirtyTracking
+
+  embeds_many :items
+  has_many    :payments
+end
+
+# After (v1.0 — restore previous behaviour for this class)
+class Order
+  include Mongoid::Document
+  include Mongoid::RelationsDirtyTracking
+
+  embeds_many :items
+  has_many    :payments
+
+  relations_dirty_tracking track_referenced: true
+end
+```
+
+If you already call `relations_dirty_tracking` with `:only` or `:except`, add
+the option to that call:
+
+```ruby
+# Before (v0.x)
+relations_dirty_tracking only: %i[items payments]
+
+# After (v1.0)
+relations_dirty_tracking only: %i[items payments], track_referenced: true
+```
+
+### When you can leave the new default
+
+Most callers can leave the new default and benefit from the speedup. Common
+cases where referenced tracking is *not* needed:
+
+- You only track embedded sub-documents (e.g. line items, addresses).
+- You use the gem to invalidate a cache or trigger a webhook when an embedded
+  collection changes.
+- Your referenced relations are also tracked through their own
+  `mongoid-history` / audit hooks on the **referenced** side, making the
+  parent-side tracking redundant.
+
 ## Contributing
 
 1. Fork it
diff --git a/lib/mongoid/relations_dirty_tracking.rb b/lib/mongoid/relations_dirty_tracking.rb
index ed0c963..cc674b0 100644
--- a/lib/mongoid/relations_dirty_tracking.rb
+++ b/lib/mongoid/relations_dirty_tracking.rb
@@ -7,6 +7,18 @@ module Mongoid
   module RelationsDirtyTracking
     extend ActiveSupport::Concern
 
+    EMBEDDED_TRACKABLES = [
+      Mongoid::Association::Embedded::EmbedsOne::Proxy,
+      Mongoid::Association::Embedded::EmbedsMany::Proxy
+    ].freeze
+
+    REFERENCED_TRACKABLES = [
+      Mongoid::Association::Referenced::HasOne::Proxy,
+      Mongoid::Association::Referenced::HasMany::Proxy,
+      Mongoid::Association::Referenced::HasAndBelongsToMany::Proxy,
+      Mongoid::Association::Referenced::BelongsTo::Proxy
+    ].freeze
+
     class << self
       DISABLED_KEY = 'mongoid/relations_dirty_tracking/disabled'
 
@@ -32,9 +44,17 @@ def thread_store
     end
 
     module ClassMethods
+      # Configure relations dirty tracking for this class.
+      #
+      # @option options [Array<Symbol,String>] :only Track only the listed relations.
+      # @option options [Array<Symbol,String>] :except Skip the listed relations.
+      # @option options [Boolean] :track_referenced Also track referenced relations
+      #   (has_one, has_many, has_and_belongs_to_many, belongs_to). Defaults to
+      #   `false` — only embedded relations are tracked by default for performance.
       def relations_dirty_tracking(options = {})
         relations_dirty_tracking_options[:only]   += [options[:only]   || []].flatten.map(&:to_s)
         relations_dirty_tracking_options[:except] += [options[:except] || []].flatten.map(&:to_s)
+        relations_dirty_tracking_options[:track_referenced] = true if options[:track_referenced]
       end
 
       def track_relation?(rel_name)
@@ -43,12 +63,8 @@ def track_relation?(rel_name)
         to_track = (!options[:only].blank? && options[:only].include?(rel_name)) ||
                    (options[:only].blank? && !options[:except].include?(rel_name))
 
-        trackables = [Mongoid::Association::Embedded::EmbedsOne::Proxy,
-                      Mongoid::Association::Embedded::EmbedsMany::Proxy,
-                      Mongoid::Association::Referenced::HasOne::Proxy,
-                      Mongoid::Association::Referenced::HasMany::Proxy,
-                      Mongoid::Association::Referenced::HasAndBelongsToMany::Proxy,
-                      Mongoid::Association::Referenced::BelongsTo::Proxy]
+        trackables = EMBEDDED_TRACKABLES
+        trackables += REFERENCED_TRACKABLES if options[:track_referenced]
 
         to_track && trackables.include?(relations[rel_name].try(:relation))
       end
@@ -63,7 +79,7 @@ def tracked_relations
       after_save       :store_relations_shadow
 
       cattr_accessor :relations_dirty_tracking_options
-      self.relations_dirty_tracking_options = { only: [], except: ['versions'] }
+      self.relations_dirty_tracking_options = { only: [], except: ['versions'], track_referenced: false }
 
       def store_relations_shadow
         @relations_shadow = {}
diff --git a/lib/mongoid/relations_dirty_tracking/version.rb b/lib/mongoid/relations_dirty_tracking/version.rb
index 36f14ea..1ff5bac 100644
--- a/lib/mongoid/relations_dirty_tracking/version.rb
+++ b/lib/mongoid/relations_dirty_tracking/version.rb
@@ -2,6 +2,6 @@
 
 module Mongoid
   module RelationsDirtyTracking
-    VERSION = '0.3.0'
+    VERSION = '1.0.0'
   end
 end
diff --git a/spec/lib/mongoid/relations_dirty_tracking_spec.rb b/spec/lib/mongoid/relations_dirty_tracking_spec.rb
index 320499b..9573a58 100644
--- a/spec/lib/mongoid/relations_dirty_tracking_spec.rb
+++ b/spec/lib/mongoid/relations_dirty_tracking_spec.rb
@@ -348,6 +348,55 @@
         expect(TestDocumentWithExceptOption.track_relation?('one_related')).to be true
       end
     end
+
+    context 'with the v1.0 default (no track_referenced option)' do
+      it 'tracks embedded relations' do
+        expect(TestDocumentDefault.track_relation?(:many_documents)).to be true
+      end
+
+      it 'does not track has_one relations' do
+        expect(TestDocumentDefault.track_relation?(:one_related)).to be false
+      end
+
+      it 'does not track has_many relations' do
+        expect(TestDocumentDefault.track_relation?(:many_related)).to be false
+      end
+    end
+  end
+
+  describe 'v1.0 default behaviour — embedded only' do
+    describe '.tracked_relations' do
+      subject { TestDocumentDefault.tracked_relations }
+
+      it { is_expected.to include('many_documents') }
+      it { is_expected.to_not include('one_related') }
+      it { is_expected.to_not include('many_related') }
+    end
+
+    describe '#relations_dirty_tracking_options' do
+      it 'defaults track_referenced to false' do
+        expect(TestDocumentDefault.relations_dirty_tracking_options[:track_referenced]).to be false
+      end
+
+      it 'is true when the macro was called with track_referenced: true' do
+        expect(TestDocument.relations_dirty_tracking_options[:track_referenced]).to be true
+      end
+    end
+
+    context 'when an embedded document is added' do
+      subject(:doc) { TestDocumentDefault.create }
+
+      before do
+        @embedded_doc = TestEmbeddedDocument.new
+        doc.many_documents << @embedded_doc
+      end
+
+      its(:relations_changed?) { is_expected.to be true }
+
+      it 'reports the embedded change' do
+        expect(doc.relation_changes['many_documents']).to eq([[], [@embedded_doc.attributes]])
+      end
+    end
   end
 
   describe 'by default the versions relation is not tracked' do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 9d2add1..1ac3e2e 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -28,7 +28,8 @@
 end
 
 Mongoid.configure do |config|
-  config.connect_to('mongoid_relations_dirty_tracking_test')
+  hosts = ENV['MONGODB_HOSTS']&.split(',') || %w[localhost:27017]
+  config.clients.default = { hosts: hosts, database: 'mongoid_relations_dirty_tracking_test' }
   config.belongs_to_required_by_default = false
 end
 
@@ -42,6 +43,9 @@ class TestDocument
   has_one     :one_related,    class_name: 'TestRelatedDocument'
   has_many    :many_related,   class_name: 'TestRelatedDocument'
   has_and_belongs_to_many :many_to_many_related, class_name: 'TestRelatedDocument'
+
+  # Tests cover both embedded and referenced behaviour, so opt in.
+  relations_dirty_tracking track_referenced: true
 end
 
 class TestEmbeddedDocument
@@ -59,6 +63,8 @@ class TestRelatedDocument
   belongs_to :test_document, inverse_of: :one_related
 
   field :title, type: String
+
+  relations_dirty_tracking track_referenced: true
 end
 
 class TestDocumentWithOnlyOption
@@ -78,5 +84,15 @@ class TestDocumentWithExceptOption
   embeds_many :many_documents,  class_name: 'TestEmbeddedDocument'
   has_one     :one_related,     class_name: 'TestRelatedDocument'
 
-  relations_dirty_tracking except: 'many_documents'
+  relations_dirty_tracking except: 'many_documents', track_referenced: true
+end
+
+# Default behaviour as of v1.0.0: embedded relations tracked, referenced ignored.
+class TestDocumentDefault
+  include Mongoid::Document
+  include Mongoid::RelationsDirtyTracking
+
+  embeds_many :many_documents, class_name: 'TestEmbeddedDocument'
+  has_one     :one_related,    class_name: 'TestRelatedDocument'
+  has_many    :many_related,   class_name: 'TestRelatedDocument'
 end