docs: some refinements on freezing

docs/performance.md

@@ -44,7 +44,7 @@ Most important observation:
 
 ### Pre-freeze data
 
-When adding a large data set to the state tree in an Immer producer (for example data received from a JSON endpoint), it is worth to call `freeze(json)` on the root of the data to be added first. This will allow Immer to add the new data to the tree faster, as it will skip _recursively_ freezing it, or searching the new data for any changes (drafts) that might be made.
+When adding a large data set to the state tree in an Immer producer (for example data received from a JSON endpoint), it is worth to call `freeze(json)` on the root of the data that is being added first. To _shallowly_ freeze it. This will allow Immer to add the new data to the tree faster, as it will avoid the need to _recursively_ scan and freeze the new data.
 
 ### You can always opt-out
 

src/core/immerClass.ts

@@ -164,7 +164,7 @@ export class Immer implements ProducersFns {
 	/**
 	 * Pass true to automatically freeze all copies created by Immer.
 	 *
-	 * By default, auto-freezing is disabled in production.
+	 * By default, auto-freezing is enabled.
 	 */
 	setAutoFreeze(value: boolean) {
 		this.autoFreeze_ = value