diff --git a/Initialization-options.md b/Initialization-options.md
index 1fbf128..a6a6294 100644
--- a/Initialization-options.md
+++ b/Initialization-options.md
@@ -14,6 +14,20 @@ If empty, cache will be stored in memory.
 
 Additional arguments or excluded arguments for `compile_commands.json` entries.
 
+## `diagnostics.onOpen: true` `diagnostics.onChange: true` `diagnostics.onSave: false`
+
+By default, diagnostics are emitted when opening a document or a change is made.
+Diagnostics require parsing the document. If it is slow for you, consider:
+
+```javascript
+{
+  "diagnostics": {
+    "onChange": false,
+    "onSave": true
+  }
+}
+```
+
 ## `index.threads`: number of indexer threads
 
 If `index.threads` is 0, use `std::thread::hardware_concurrency()`. If you want to control peak memory usage, set it to a small integer.