diff --git a/middleman-core/lib/middleman-core/config_context.rb b/middleman-core/lib/middleman-core/config_context.rb
index ebf0d67c..3ee98632 100644
--- a/middleman-core/lib/middleman-core/config_context.rb
+++ b/middleman-core/lib/middleman-core/config_context.rb
@@ -23,7 +23,7 @@ module Middleman
     end
 
     def include(mod)
-      self.extend(mod)
+      extend(mod)
     end
 
     def helpers(*helper_modules, &block)
diff --git a/middleman-core/lib/middleman-core/core_extensions/front_matter.rb b/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
index 49f4195f..0f69c634 100644
--- a/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
@@ -73,18 +73,20 @@ module Middleman::CoreExtensions
 
       return [{}, nil] unless file
 
-      return @cache[file[:full_path]] if @cache.key?(file[:full_path])
+      file_path = file[:full_path].to_s
 
-      @cache[file[:full_path]] = ::Middleman::Util::Data.parse(
-        file,
-        app.config[:frontmatter_delims]
-      )
+      @cache[file_path] ||= begin
+        ::Middleman::Util::Data.parse(
+          file,
+          app.config[:frontmatter_delims]
+        )
+      end
     end
 
     Contract ArrayOf[IsA['Middleman::SourceFile']], ArrayOf[IsA['Middleman::SourceFile']] => Any
     def clear_data(updated_files, removed_files)
       (updated_files + removed_files).each do |file|
-        @cache.delete(file[:full_path])
+        @cache.delete(file[:full_path].to_s)
       end
     end
   end
diff --git a/middleman-core/lib/middleman-core/core_extensions/inline_url_rewriter.rb b/middleman-core/lib/middleman-core/core_extensions/inline_url_rewriter.rb
index 14cf4715..24d541fa 100644
--- a/middleman-core/lib/middleman-core/core_extensions/inline_url_rewriter.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/inline_url_rewriter.rb
@@ -1,6 +1,6 @@
 require 'rack'
 require 'rack/response'
-require 'addressable/uri'
+require 'memoist'
 require 'middleman-core/util'
 require 'middleman-core/contracts'
 
@@ -33,6 +33,8 @@ module Middleman
       end
 
       def after_configuration
+        return if @rewriters.empty?
+
         rewriters = @rewriters.values.sort do |a, b|
           if b[:after] && b[:after] == a[:id]
             1
@@ -45,6 +47,7 @@ module Middleman
       end
 
       class Rack
+        extend Memoist
         include Contracts
 
         Contract RespondTo[:call], {
@@ -55,6 +58,17 @@ module Middleman
           @rack_app = app
           @middleman_app = options.fetch(:middleman_app)
           @rewriters = options.fetch(:rewriters)
+
+          all_source_exts = @rewriters
+                            .reduce([]) { |sum, rewriter| sum + rewriter[:source_extensions] }
+                            .flatten
+                            .uniq
+          @source_exts_regex_text = Regexp.union(all_source_exts).to_s
+
+          @all_asset_exts = @rewriters
+                            .reduce([]) { |sum, rewriter| sum + rewriter[:url_extensions] }
+                            .flatten
+                            .uniq
         end
 
         def call(env)
@@ -63,27 +77,16 @@ module Middleman
           # Allow configuration or upstream request to skip all rewriting
           return [status, headers, response] if env['bypass_inline_url_rewriter'] == 'true'
 
-          all_source_exts = @rewriters
-                            .reduce([]) { |sum, rewriter| sum + rewriter[:source_extensions] }
-                            .flatten
-                            .uniq
-          source_exts_regex_text = Regexp.union(all_source_exts).to_s
-
-          all_asset_exts = @rewriters
-                           .reduce([]) { |sum, rewriter| sum + rewriter[:url_extensions] }
-                           .flatten
-                           .uniq
-
           path = ::Middleman::Util.full_path(env['PATH_INFO'], @middleman_app)
 
-          return [status, headers, response] unless path =~ /(^\/$)|(#{source_exts_regex_text}$)/
+          return [status, headers, response] unless path =~ /(^\/$)|(#{@source_exts_regex_text}$)/
           return [status, headers, response] unless body = ::Middleman::Util.extract_response_text(response)
 
           dirpath = ::Pathname.new(File.dirname(path))
 
           rewritten = ::Middleman::Util.instrument 'inline_url_rewriter', path: path do
-            ::Middleman::Util.rewrite_paths(body, path, all_asset_exts, @middleman_app) do |asset_path|
-              uri = ::Addressable::URI.parse(asset_path)
+            ::Middleman::Util.rewrite_paths(body, path, @all_asset_exts, @middleman_app) do |asset_path|
+              uri = ::Middleman::Util.parse_uri(asset_path)
 
               relative_path = uri.host.nil?
 
@@ -144,6 +147,7 @@ module Middleman
             false
           end
         end
+        memoize :should_ignore?
       end
     end
   end
diff --git a/middleman-core/lib/middleman-core/extension.rb b/middleman-core/lib/middleman-core/extension.rb
index 8f342e69..9805455a 100644
--- a/middleman-core/lib/middleman-core/extension.rb
+++ b/middleman-core/lib/middleman-core/extension.rb
@@ -1,4 +1,5 @@
 require 'forwardable'
+require 'memoist'
 require 'active_support/core_ext/class/attribute'
 require 'middleman-core/configuration'
 require 'middleman-core/contracts'
@@ -66,6 +67,8 @@ module Middleman
   # @see http://middlemanapp.com/advanced/custom/ Middleman Custom Extensions Documentation
   class Extension
     extend Forwardable
+    extend Memoist
+
     include Contracts
 
     def_delegator :@app, :logger
@@ -510,7 +513,7 @@ module Middleman
       self.class.exposed_to_config.each do |k, v|
         ::Middleman::CoreExtensions::Collections::StepContext.add_to_context(k) do |*args, &b|
           r = context.method(:"__original_#{v}").call(*args, &b)
-          self.descriptors << r if r.respond_to?(:execute_descriptor)
+          descriptors << r if r.respond_to?(:execute_descriptor)
         end
       end
     end
diff --git a/middleman-core/lib/middleman-core/extensions/asset_hash.rb b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
index b38bab9f..b0b955f9 100644
--- a/middleman-core/lib/middleman-core/extensions/asset_hash.rb
+++ b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
@@ -32,7 +32,7 @@ class Middleman::Extensions::AssetHash < ::Middleman::Extension
 
   Contract String, Or[String, Pathname], Any => Maybe[String]
   def rewrite_url(asset_path, dirpath, _request_path)
-    uri = ::Addressable::URI.parse(asset_path)
+    uri = ::Middleman::Util.parse_uri(asset_path)
     relative_path = !uri.path.start_with?('/')
 
     full_asset_path = if relative_path
diff --git a/middleman-core/lib/middleman-core/extensions/asset_host.rb b/middleman-core/lib/middleman-core/extensions/asset_host.rb
index f7c7e8fc..7cb83d07 100644
--- a/middleman-core/lib/middleman-core/extensions/asset_host.rb
+++ b/middleman-core/lib/middleman-core/extensions/asset_host.rb
@@ -20,7 +20,7 @@ class Middleman::Extensions::AssetHost < ::Middleman::Extension
 
   Contract String, Or[String, Pathname], Any => String
   def rewrite_url(asset_path, dirpath, _request_path)
-    uri = ::Addressable::URI.parse(asset_path)
+    uri = ::Middleman::Util.parse_uri(asset_path)
     relative_path = uri.path[0..0] != '/'
 
     full_asset_path = if relative_path
@@ -37,4 +37,5 @@ class Middleman::Extensions::AssetHost < ::Middleman::Extension
 
     File.join(asset_prefix, full_asset_path)
   end
+  memoize :rewrite_url
 end
diff --git a/middleman-core/lib/middleman-core/extensions/minify_css.rb b/middleman-core/lib/middleman-core/extensions/minify_css.rb
index cc513b6c..067b25bf 100644
--- a/middleman-core/lib/middleman-core/extensions/minify_css.rb
+++ b/middleman-core/lib/middleman-core/extensions/minify_css.rb
@@ -1,3 +1,4 @@
+require 'memoist'
 require 'middleman-core/contracts'
 
 # Minify CSS Extension
@@ -30,6 +31,7 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
 
   # Rack middleware to look for CSS and compress it
   class Rack
+    extend Memoist
     include Contracts
     INLINE_CSS_REGEX = /(<style[^>]*>\s*(?:\/\*<!\[CDATA\[\*\/\n)?)(.*?)((?:(?:\n\s*)?\/\*\]\]>\*\/)?\s*<\/style>)/m
 
@@ -82,8 +84,9 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
     # @param [String] path
     # @return [Boolean]
     def ignore?(path)
-      @ignore.any? { |ignore| Middleman::Util.path_match(ignore, path) }
+      @ignore.any? { |ignore| ::Middleman::Util.path_match(ignore, path) }
     end
+    memoize :ignore?
 
     # Whether this type of content can be minified
     # @param [String, nil] content_type
@@ -91,6 +94,7 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
     def minifiable?(content_type)
       @content_types.include?(content_type)
     end
+    memoize :minifiable?
 
     # Whether this type of content contains inline content that can be minified
     # @param [String, nil] content_type
@@ -98,6 +102,7 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
     def minifiable_inline?(content_type)
       @inline_content_types.include?(content_type)
     end
+    memoize :minifiable_inline?
 
     # Minify the content
     # @param [String] content
@@ -105,6 +110,7 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
     def minify(content)
       @compressor.compress(content)
     end
+    memoize :minify
 
     # Detect and minify inline content
     # @param [String] content
@@ -114,5 +120,6 @@ class Middleman::Extensions::MinifyCss < ::Middleman::Extension
         $1 + minify($2) + $3
       end
     end
+    memoize :minify_inline
   end
 end
diff --git a/middleman-core/lib/middleman-core/extensions/minify_javascript.rb b/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
index acd71224..48490470 100644
--- a/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
+++ b/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
@@ -1,4 +1,5 @@
 require 'middleman-core/contracts'
+require 'memoist'
 
 # Minify Javascript Extension
 class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
@@ -22,6 +23,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
 
   # Rack middleware to look for JS and compress it
   class Rack
+    extend Memoist
     include Contracts
     INLINE_JS_REGEX = /(<script[^>]*>\s*(?:\/\/(?:(?:<!--)|(?:<!\[CDATA\[))\n)?)(.*?)((?:(?:\n\s*)?\/\/(?:(?:-->)|(?:\]\]>)))?\s*<\/script>)/m
 
@@ -76,6 +78,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
     def ignore?(path)
       @ignore.any? { |ignore| Middleman::Util.path_match(ignore, path) }
     end
+    memoize :ignore?
 
     # Whether this type of content can be minified
     # @param [String, nil] content_type
@@ -83,6 +86,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
     def minifiable?(content_type)
       @content_types.include?(content_type)
     end
+    memoize :minifiable?
 
     # Whether this type of content contains inline content that can be minified
     # @param [String, nil] content_type
@@ -90,6 +94,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
     def minifiable_inline?(content_type)
       @inline_content_types.include?(content_type)
     end
+    memoize :minifiable_inline?
 
     # Minify the content
     # @param [String] content
@@ -100,6 +105,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
       warn "WARNING: Couldn't compress JavaScript in #{@path}: #{e.message}"
       content
     end
+    memoize :minify
 
     # Detect and minify inline content
     # @param [String] content
@@ -119,5 +125,6 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
         end
       end
     end
+    memoize :minify_inline
   end
 end
diff --git a/middleman-core/lib/middleman-core/extensions/relative_assets.rb b/middleman-core/lib/middleman-core/extensions/relative_assets.rb
index b319de1b..33ac420e 100644
--- a/middleman-core/lib/middleman-core/extensions/relative_assets.rb
+++ b/middleman-core/lib/middleman-core/extensions/relative_assets.rb
@@ -33,7 +33,7 @@ class Middleman::Extensions::RelativeAssets < ::Middleman::Extension
 
   Contract String, Or[String, Pathname], Any => Maybe[String]
   def rewrite_url(asset_path, dirpath, request_path)
-    uri = ::Addressable::URI.parse(asset_path)
+    uri = ::Middleman::Util.parse_uri(asset_path)
 
     return if uri.path[0..0] != '/'
 
@@ -50,4 +50,5 @@ class Middleman::Extensions::RelativeAssets < ::Middleman::Extension
 
     result
   end
+  memoize :rewrite_url
 end
diff --git a/middleman-core/lib/middleman-core/file_renderer.rb b/middleman-core/lib/middleman-core/file_renderer.rb
index ae1212b4..a3e8b193 100644
--- a/middleman-core/lib/middleman-core/file_renderer.rb
+++ b/middleman-core/lib/middleman-core/file_renderer.rb
@@ -59,7 +59,7 @@ module Middleman
       # Overwrite with frontmatter options
       options = options.deep_merge(options[:renderer_options]) if options[:renderer_options]
 
-      template_class = ::Tilt[path]
+      template_class = ::Middleman::Util.tilt_class(path)
 
       # Allow hooks to manipulate the template before render
       body = @app.callbacks_for(:before_render).reduce(body) do |sum, callback|
@@ -99,12 +99,12 @@ module Middleman
     def template_data_for_file
       file = @app.files.find(:source, @path)
 
-      if @app.extensions[:front_matter] || (file && !file[:types].include?(:no_frontmatter))
+      if @app.extensions[:front_matter] && (file && !file[:types].include?(:no_frontmatter))
         result = @app.extensions[:front_matter].template_data_for_file(@path)
         return result unless result.nil?
       end
 
-      file ? file.read : File.read(@path)
+      file ? file.read : ::File.read(@path)
     end
 
     protected
@@ -122,7 +122,7 @@ module Middleman
 
         # Find all the engines which handle this extension in tilt. Look for
         # config variables of that name and merge it
-        extension_class = ::Tilt[ext]
+        extension_class = ::Middleman::Util.tilt_class(ext)
         ::Tilt.mappings.each do |mapping_ext, engines|
           next unless engines.include? extension_class
           engine_options = @app.config[mapping_ext.to_sym] || {}
diff --git a/middleman-core/lib/middleman-core/sitemap/resource.rb b/middleman-core/lib/middleman-core/sitemap/resource.rb
index fd236f3f..7c18078f 100644
--- a/middleman-core/lib/middleman-core/sitemap/resource.rb
+++ b/middleman-core/lib/middleman-core/sitemap/resource.rb
@@ -75,7 +75,7 @@ module Middleman
       Contract Bool
       def template?
         return false if file_descriptor.nil?
-        !::Tilt[file_descriptor[:full_path].to_s].nil?
+        !::Middleman::Util.tilt_class(file_descriptor[:full_path].to_s).nil?
       end
 
       # Backwards compatible method for turning descriptor into a string.
diff --git a/middleman-core/lib/middleman-core/sources/source_watcher.rb b/middleman-core/lib/middleman-core/sources/source_watcher.rb
index 2c034570..9852e223 100644
--- a/middleman-core/lib/middleman-core/sources/source_watcher.rb
+++ b/middleman-core/lib/middleman-core/sources/source_watcher.rb
@@ -298,9 +298,15 @@ module Middleman
       relative_path = path.relative_path_from(directory)
       relative_path = File.join(destination_dir, relative_path) if destination_dir
 
+      types << :no_frontmatter if partial?(relative_path.to_s)
+
       ::Middleman::SourceFile.new(Pathname(relative_path), path, directory, types, 0)
     end
 
+    def partial?(relative_path)
+      relative_path.split(::File::SEPARATOR).any? { |p| p.start_with?('_') }
+    end
+
     Contract IsA['Middleman::SourceFile'] => Any
     def record_file_change(f)
       if @files[f[:full_path]]
diff --git a/middleman-core/lib/middleman-core/template_context.rb b/middleman-core/lib/middleman-core/template_context.rb
index 99ec6ee5..ca5f3632 100644
--- a/middleman-core/lib/middleman-core/template_context.rb
+++ b/middleman-core/lib/middleman-core/template_context.rb
@@ -84,6 +84,7 @@ module Middleman
         # Reset stored buffer, regardless of success
         restore_buffer(buf_was)
       end
+
       # Render the layout, with the contents of the block inside.
       concat_safe_content render_file(layout_file, @locs, @opts) { content }
     ensure
@@ -185,7 +186,7 @@ module Middleman
       # handles cases like `style.css.sass.erb`
       content = nil
 
-      while ::Tilt[path]
+      while ::Middleman::Util.tilt_class(path)
         begin
           opts[:template_body] = content if content
 
diff --git a/middleman-core/lib/middleman-core/template_renderer.rb b/middleman-core/lib/middleman-core/template_renderer.rb
index 1cf9febf..0dcf2af8 100644
--- a/middleman-core/lib/middleman-core/template_renderer.rb
+++ b/middleman-core/lib/middleman-core/template_renderer.rb
@@ -61,7 +61,7 @@ module Middleman
 
       # If we're specifically looking for a preferred engine
       if options.key?(:preferred_engine)
-        extension_class = ::Tilt[options[:preferred_engine]]
+        extension_class = ::Middleman::Util.tilt_class(options[:preferred_engine])
 
         # Get a list of extensions for a preferred engine
         preferred_engines += ::Tilt.mappings.select do |_, engines|
@@ -89,7 +89,7 @@ module Middleman
           app.files.find(:source, path_with_ext, globbing)
         end
 
-        found_template = file if file && (preferred_engine.nil? || ::Tilt[file[:full_path]])
+        found_template = file if file && (preferred_engine.nil? || ::Middleman::Util.tilt_class(file[:full_path].to_s))
         break if found_template
       end
 
@@ -134,9 +134,9 @@ module Middleman
       @app.extensions.add_exposed_to_context(context)
 
       locals.each do |k, _|
-        next unless context.respond_to?(k) && k != :current_path
+        next unless context.respond_to?(k) && ![:current_path, :paginate, :page_articles, :blog_controller, :lang, :locale].include?(k.to_sym)
 
-        msg = "Template local `#{k}` tried to overwrite an existing context value. Please renamed the key when passing to `locals`"
+        msg = "Template local `#{k}` tried to overwrite an existing context value. Please rename the key when passing to `locals`"
 
         if @app.build?
           throw msg
@@ -152,13 +152,14 @@ module Middleman
       # If we need a layout and have a layout, use it
       layout_file = fetch_layout(engine, options)
       if layout_file
-        content = ::Middleman::Util.instrument 'builder.output.resource.render-layout', path: File.basename(layout_file[:relative_path].to_s) do
-          if layout_file = fetch_layout(engine, options)
-            layout_renderer = ::Middleman::FileRenderer.new(@app, layout_file[:relative_path].to_s)
+        content = if layout_file = fetch_layout(engine, options)
+          layout_renderer = ::Middleman::FileRenderer.new(@app, layout_file[:relative_path].to_s)
+
+          ::Middleman::Util.instrument 'builder.output.resource.render-layout', path: File.basename(layout_file[:relative_path].to_s) do
             layout_renderer.render(locals, options, context) { content }
-          else
-            content
           end
+        else
+          content
         end
       end
 
@@ -177,7 +178,7 @@ module Middleman
       # handles cases like `style.css.sass.erb`
       content = nil
 
-      while ::Tilt[path]
+      while ::Middleman::Util.tilt_class(path)
         begin
           opts[:template_body] = content if content
 
diff --git a/middleman-core/lib/middleman-core/util/data.rb b/middleman-core/lib/middleman-core/util/data.rb
index 1a521b8d..ce73540a 100644
--- a/middleman-core/lib/middleman-core/util/data.rb
+++ b/middleman-core/lib/middleman-core/util/data.rb
@@ -3,6 +3,7 @@ require 'json'
 require 'pathname'
 require 'backports/2.1.0/array/to_h'
 require 'hashie'
+require 'memoist'
 
 require 'middleman-core/util/binary'
 require 'middleman-core/contracts'
@@ -36,6 +37,7 @@ module Middleman
     end
 
     module Data
+      extend Memoist
       include Contracts
 
       module_function
@@ -55,20 +57,7 @@ module Middleman
           return [{}, nil]
         end
 
-        start_delims, stop_delims = frontmatter_delims
-                                    .values
-                                    .flatten(1)
-                                    .transpose
-                                    .map(&::Regexp.method(:union))
-
-        match = /
-          \A(?:[^\r\n]*coding:[^\r\n]*\r?\n)?
-          (?<start>#{start_delims})[ ]*\r?\n
-          (?<frontmatter>.*?)[ ]*\r?\n?
-          ^(?<stop>#{stop_delims})[ ]*\r?\n?
-          \r?\n?
-          (?<additional_content>.*)
-        /mx.match(content) || {}
+        match = build_regex(frontmatter_delims).match(content) || {}
 
         unless match[:frontmatter]
           case known_type
@@ -98,27 +87,53 @@ module Middleman
         end
       end
 
+      def build_regex(frontmatter_delims)
+        start_delims, stop_delims = frontmatter_delims
+                                    .values
+                                    .flatten(1)
+                                    .transpose
+                                    .map(&::Regexp.method(:union))
+
+        match = /
+          \A(?:[^\r\n]*coding:[^\r\n]*\r?\n)?
+          (?<start>#{start_delims})[ ]*\r?\n
+          (?<frontmatter>.*?)[ ]*\r?\n?
+          ^(?<stop>#{stop_delims})[ ]*\r?\n?
+          \r?\n?
+          (?<additional_content>.*)
+        /mx
+      end
+      memoize :build_regex
+
       # Parse YAML frontmatter out of a string
       # @param [String] content
       # @return [Hash]
-      Contract String, Pathname, Bool => Hash
+      Contract String, Pathname => Hash
       def parse_yaml(content, full_path)
-        symbolize_recursive(::YAML.load(content) || {})
+        c = ::Middleman::Util.instrument 'parse.yaml' do
+          ::YAML.load(content)
+        end
+        c ? symbolize_recursive(c) : {}
       rescue StandardError, ::Psych::SyntaxError => error
         warn "YAML Exception parsing #{full_path}: #{error.message}"
         {}
       end
+      memoize :parse_yaml
 
       # Parse JSON frontmatter out of a string
       # @param [String] content
       # @return [Hash]
       Contract String, Pathname => Hash
       def parse_json(content, full_path)
-        symbolize_recursive(::JSON.parse(content) || {})
+        c = ::Middleman::Util.instrument 'parse.json' do
+          ::JSON.parse(content)
+        end
+        c ? symbolize_recursive(c) : {}
       rescue StandardError => error
         warn "JSON Exception parsing #{full_path}: #{error.message}"
         {}
       end
+      memoize :parse_json
 
       def symbolize_recursive(value)
         case value
diff --git a/middleman-core/lib/middleman-core/util/files.rb b/middleman-core/lib/middleman-core/util/files.rb
index 9ba716f3..e57179a4 100644
--- a/middleman-core/lib/middleman-core/util/files.rb
+++ b/middleman-core/lib/middleman-core/util/files.rb
@@ -54,15 +54,9 @@ module Middleman
       result.encode('UTF-8', 'UTF-8-MAC')
     end
 
-    Contract String => Bool
-    def tilt_recognizes?(path)
-      @@tilt_lookup_cache ||= {}
-      @@tilt_lookup_cache[path] ||= ::Tilt[path]
-    end
-
     Contract String => String
     def step_through_extensions(path)
-      while tilt_recognizes?(path)
+      while ::Middleman::Util.tilt_class(path)
         ext = ::File.extname(path)
         yield ext if block_given?
 
diff --git a/middleman-core/lib/middleman-core/util/paths.rb b/middleman-core/lib/middleman-core/util/paths.rb
index 97abf218..fa25e818 100644
--- a/middleman-core/lib/middleman-core/util/paths.rb
+++ b/middleman-core/lib/middleman-core/util/paths.rb
@@ -1,16 +1,32 @@
 # Core Pathname library used for traversal
 require 'pathname'
 require 'uri'
+require 'memoist'
+require 'addressable'
+require 'tilt'
 
 require 'middleman-core/contracts'
 
 # rubocop:disable ModuleLength
 module Middleman
   module Util
+    extend Memoist
     include Contracts
 
     module_function
 
+    Contract String => ::Addressable::URI
+    def parse_uri(uri)
+      ::Addressable::URI.parse(uri)
+    end
+    memoize :parse_uri
+
+    Contract String => Any
+    def tilt_class(path)
+      ::Tilt[path]
+    end
+    memoize :tilt_class
+
     # Normalize a path to not include a leading slash
     # @param [String] path
     # @return [String]
@@ -19,6 +35,7 @@ module Middleman
       # The tr call works around a bug in Ruby's Unicode handling
       ::URI.decode(path).sub(%r{^/}, '').tr('', '')
     end
+    memoize :normalize_path
 
     # This is a separate method from normalize_path in case we
     # change how we normalize paths
@@ -26,6 +43,7 @@ module Middleman
     def strip_leading_slash(path)
       path.sub(%r{^/}, '')
     end
+    memoize :strip_leading_slash
 
     # Get the path of a file of a given type
     #
@@ -256,5 +274,6 @@ module Middleman
         ::File.fnmatch(matcher.to_s, path)
       end
     end
+    memoize :path_match
   end
 end
diff --git a/middleman-core/lib/middleman-core/util/rack.rb b/middleman-core/lib/middleman-core/util/rack.rb
index 0aeda851..2459052b 100644
--- a/middleman-core/lib/middleman-core/util/rack.rb
+++ b/middleman-core/lib/middleman-core/util/rack.rb
@@ -38,7 +38,7 @@ module Middleman
         current_resource = app.sitemap.find_resource_by_destination_path(path)
 
         begin
-          uri = ::Addressable::URI.parse(asset_path)
+          uri = ::Middleman::Util.parse_uri(asset_path)
 
           if uri.relative? && uri.host.nil? && !(asset_path =~ /^[^\/].*[a-z]+\.[a-z]+\/.*/)
             dest_path = ::Middleman::Util.url_for(app, asset_path, relative: false, current_resource: current_resource)
diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index a589eb56..acea6a07 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -31,6 +31,7 @@ Gem::Specification.new do |s|
   s.add_dependency('activesupport', ['~> 4.2'])
   s.add_dependency('padrino-helpers', ['~> 0.13.0'])
   s.add_dependency("addressable", ["~> 2.3"])
+  s.add_dependency('memoist', ['~> 0.14'])
 
   # Watcher
   s.add_dependency('listen', ['~> 3.0'])