2 files changed, 7 insertions, 3 deletions
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
index 792076a449..f2ba7fdda5 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
@@ -300,7 +300,7 @@ module DateAndTime
     end
 
     # Returns a Range representing the whole week of the current date/time.
-    # Week starts on start_day, default is <tt>Date.week_start</tt> or <tt>config.week_start</tt> when set.
+    # Week starts on start_day, default is <tt>Date.beginning_of_week</tt> or <tt>config.beginning_of_week</tt> when set.
     def all_week(start_day = Date.beginning_of_week)
       beginning_of_week(start_day)..end_of_week(start_day)
     end
@@ -334,7 +334,7 @@ module DateAndTime
       end
 
       def copy_time_to(other)
-        other.change(hour: hour, min: min, sec: sec, usec: try(:usec))
+        other.change(hour: hour, min: min, sec: sec, nsec: try(:nsec))
       end
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb b/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
index 3f4e236ab7..db95ae0db5 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
@@ -12,7 +12,11 @@ module DateAndTime
     mattr_accessor(:preserve_timezone, instance_writer: false) { false }
 
     def to_time
-      preserve_timezone ? getlocal(utc_offset) : getlocal
+      if preserve_timezone
+        @_to_time_with_instance_offset ||= getlocal(utc_offset)
+      else
+        @_to_time_with_system_offset ||= getlocal
+      end
     end
   end
 end