Skip redundant preference re-serialization on load

core/app/models/concerns/spree/preferences/persistable.rb

@@ -20,9 +20,10 @@ module Persistable
       private
 
       def initialize_preference_defaults
-        if has_attribute?(:preferences)
-          self.preferences = default_preferences.merge(preferences)
-        end
+        return unless has_attribute?(:preferences)
+
+        merged = default_preferences.merge(preferences)
+        self.preferences = merged unless merged == preferences
       end
     end
   end

core/spec/models/spree/preferences/preferable_spec.rb

@@ -387,6 +387,17 @@ class ComplexPreferableClass
       end
     end
 
+    it "does not re-serialize unchanged preferences when read after load" do
+      loaded = PrefTest.find(@pt.id)
+
+      # NOTE: assigning preferences in after_initialize (even an identical value) flips
+      # the attribute to "from user" state, so every later read re-dumps YAML. Skipping
+      # the redundant assignment keeps reads on the cheaper "from database" path.
+      expect(Psych).not_to receive(:safe_dump)
+
+      loaded.preferences
+    end
+
     it "clear preferences when record is deleted" do
       @pt.save!
       @pt.preferred_pref_test_pref = "lmn"