style and comments

lib/zeitwerk/loader.rb

@@ -616,6 +616,9 @@ def set_autoload(parent, cname, abspath)
       # $LOADED_FEATURES stores real paths since Ruby 2.4.4. We set and save the
       # real path to be able to delete it from $LOADED_FEATURES on unload, and to
       # be able to do a lookup later in Kernel#require for manual require calls.
+      #
+      # We freeze realpath because that saves allocations in Module#autoload.
+      # See #125.
       realpath = File.realpath(abspath).freeze
       parent.autoload(cname, realpath)
       if logger
@@ -719,8 +722,13 @@ def cpath(parent, cname)
     def ls(dir)
       Dir.foreach(dir) do |basename|
         next if basename.start_with?(".")
-        abspath = File.join(dir, basename).freeze
-        yield basename, abspath unless ignored_paths.member?(abspath)
+
+        abspath = File.join(dir, basename)
+        next if ignored_paths.member?(abspath)
+
+        # We freeze abspath because that saves allocations when passed later to
+        # File methods. See #125.
+        yield basename, abspath.freeze
       end
     end