README.md in propshaft-0.6.4 vs README.md in propshaft-0.7.0

@@ -25,9 +25,19 @@
 
 ## Bypassing the digest step
 
 If you need to put multiple files that refer to each other through Propshaft, like a JavaScript file and its source map, you have to digest these files in advance to retain stable file names. Propshaft looks for the specific pattern of `-[digest].digested.js` as the postfix to any asset file as an indication that the file has already been digested.
 
+## Improving performance in development
+
+Before every request Propshaft checks if any asset was updated to decide if a cache sweep is needed. This verification is done using the application's configured file watcher which, by default, is `ActiveSupport::FileUpdateChecker`. 
+
+If you have a lot of assets in your project, you can improve performance by adding the `listen` gem to the development group in your Gemfile, and this line to the `development.rb` environment file:
+
+```ruby
+config.file_watcher = ActiveSupport::EventedFileUpdateChecker
+```
+
 
 ## Migrating from Sprockets
 
 Propshaft does a lot less than Sprockets, by design, so it might well be a fair bit of work to migrate if it's even desirable. This is particularly true if you rely on Sprockets to provide any form of transpiling, like CoffeeScript or Sass, or if you rely on any gems that do. You'll need to either stop transpiling or use a Node-based transpiler, like those in [`jsbundling-rails`](https://github.com/rails/jsbundling-rails) and [`cssbundling-rails`](https://github.com/rails/cssbundling-rails).