From 4943dbf577b8c65b7994d979c2963d688e42f6c0 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Thu, 6 Oct 2022 15:27:13 +0000
Subject: [PATCH] Themes: Replace `array_map()` usage in
 `WP_Theme_JSON::get_default_slugs()`.

When loading a page on the frontend using Xdebug & Webgrind, with the Twenty Twenty-Three theme and no plugins activated, the biggest performance bottleneck currently (on the PHP side) is `WP_Theme_JSON::merge()`. Analysing the data a bit more, it became evident that `WP_Theme_JSON::get_default_slugs()` is the part of that method which takes most of the resources and time.

Further analysis of the method revealed that `array_map()` was the call that slowed it down.

This commit replaces the `array_map()` call with a simple `foreach` loop, improving page load speed significantly.

Follow-up to [52275], [52364].

Props aristath.
Fixes #56745.
Built from https://develop.svn.wordpress.org/trunk@54398


git-svn-id: http://core.svn.wordpress.org/trunk@53957 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/class-wp-theme-json.php | 12 ++++++------
 wp-includes/version.php             |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/wp-includes/class-wp-theme-json.php b/wp-includes/class-wp-theme-json.php
index 1774c5ef6f..40262661e4 100644
--- a/wp-includes/class-wp-theme-json.php
+++ b/wp-includes/class-wp-theme-json.php
@@ -2422,12 +2422,12 @@ class WP_Theme_JSON {
 			}
 
 			$slugs_for_preset = array();
-			$slugs_for_preset = array_map(
-				static function( $value ) {
-					return isset( $value['slug'] ) ? $value['slug'] : null;
-				},
-				$preset
-			);
+			foreach ( $preset as $item ) {
+				if ( isset( $item['slug'] ) ) {
+					$slugs_for_preset[] = $item['slug'];
+				}
+			}
+
 			_wp_array_set( $slugs, $metadata['path'], $slugs_for_preset );
 		}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e154003dc4..06c45e045a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-beta3-54397';
+$wp_version = '6.1-beta3-54398';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.