ConfigurationFile: skip ERB rendering unless the file seem to contain ERB

Uncached ERB rendering is very costly, so assuming many files don't
actually contain ERB, it's worth checking for it first.

For ERB file, we could consider caching the compilation, but it's
more complicated.

Author: byroot

activesupport/lib/active_support/configuration_file.rb

@@ -19,7 +19,8 @@ def self.parse(content_path, **options)
     end
 
     def parse(context: nil, **options)
-      source = render(context)
+      source = @content.include?("<%") ? render(context) : @content
+
       if source == @content
         if YAML.respond_to?(:unsafe_load)
           YAML.unsafe_load_file(@content_path, **options) || {}
@@ -42,7 +43,6 @@ def parse(context: nil, **options)
     private
       def read(content_path)
         require "yaml" unless defined?(YAML)
-        require "erb" unless defined?(ERB)
 
         File.read(content_path).tap do |content|
           if content.include?("\u00A0")
@@ -52,6 +52,7 @@ def read(content_path)
       end
 
       def render(context)
+        require "erb" unless defined?(ERB)
         erb = ERB.new(@content).tap { |e| e.filename = @content_path }
         context ? erb.result(context) : erb.result
       end