README.md in batch-loader-1.3.0 vs README.md in batch-loader-1.4.0

@@ -18,10 +18,11 @@
   * [RESTful API example](#restful-api-example)
   * [GraphQL example](#graphql-example)
   * [Loading multiple items](#loading-multiple-items)
   * [Batch key](#batch-key)
   * [Caching](#caching)
+  * [Replacing methods](#replacing-methods)
 * [Installation](#installation)
 * [API](#api)
 * [Implementation details](#implementation-details)
 * [Development](#development)
 * [Contributing](#contributing)
@@ -372,10 +373,25 @@
 
 puts user_lazy(1) # SELECT * FROM users WHERE id IN (1)
 puts user_lazy(1) # SELECT * FROM users WHERE id IN (1)
 ```
 
+If you set `cache: false`, it's likely you also want `replace_methods: false` (see below section).
+
+### Replacing methods
+
+By default, `BatchLoader` replaces methods on its instance by calling `#define_method` after batching to copy methods from the loaded value.
+This consumes some time but allows to speed up any future method calls on the instance.
+In some cases, when there are a lot of instances with a huge number of defined methods, this initial process of replacing the methods can be slow.
+You may consider avoiding the "up front payment" and "pay as you go" with `#method_missing` by disabling the method replacement:
+
+```ruby
+BatchLoader.for(id).batch(replace_methods: false) do |ids, loader|
+  # ...
+end
+```
+
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
@@ -391,23 +407,29 @@
     $ gem install batch-loader
 
 ## API
 
 ```ruby
-BatchLoader.for(item).batch(default_value: default_value, cache: cache, key: key) do |items, loader, args|
+BatchLoader.for(item).batch(
+  default_value: default_value,
+  cache: cache,
+  replace_methods: replace_methods,
+  key: key
+) do |items, loader, args|
   # ...
 end
 ```
 
-| Argument Key    | Default                                       | Description                                                   |
-| --------------- | --------------------------------------------- | ------------------------------------------------------------- |
-| `item`          | -                                             | Item which will be collected and used for batching.           |
-| `default_value` | `nil`                                         | Value returned by default after batching.                     |
-| `cache`         | `true`                                        | Set `false` to disable caching between the same executions.   |
-| `key`           | `nil`                                         | Pass custom key to uniquely identify the batch block.         |
-| `items`         | -                                             | List of collected items for batching.                         |
-| `loader`        | -                                             | Lambda which should be called to load values loaded in batch. |
-| `args`          | `{default_value: nil, cache: true, key: nil}` | Arguments passed to the `batch` method.                       |
+| Argument Key      | Default                                                              | Description                                                                           |
+| ---------------   | ---------------------------------------------                        | -------------------------------------------------------------                         |
+| `item`            | -                                                                    | Item which will be collected and used for batching.                                   |
+| `default_value`   | `nil`                                                                | Value returned by default after batching.                                             |
+| `cache`           | `true`                                                               | Set `false` to disable caching between the same executions.                           |
+| `replace_methods` | `true`                                                               | Set `false` to use `#method_missing` instead of replacing the methods after batching. |
+| `key`             | `nil`                                                                | Pass custom key to uniquely identify the batch block.                                 |
+| `items`           | -                                                                    | List of collected items for batching.                                                 |
+| `loader`          | -                                                                    | Lambda which should be called to load values loaded in batch.                         |
+| `args`            | `{default_value: nil, cache: true, replace_methods: true, key: nil}` | Arguments passed to the `batch` method.                                               |
 
 ## Implementation details
 
 See the [slides](https://speakerdeck.com/exaspark/batching-a-powerful-way-to-solve-n-plus-1-queries) [37-42].