Administration: Improve performance of List Tables.

Improve the performance of `WP_List_Table::get_column_info()` by adding the primary column to the cached header values. This reduces the number of calls to the `WP_List_Table::get_primary_column_name()` method to once per table in line with the other header getter functions.

Props bobbingwide, chaion07, costdev, mikeschroder, mukesh27, peterwilsoncc, shetheliving, spacedmonkey.
Fixes #34564.


Built from https://develop.svn.wordpress.org/trunk@53868


git-svn-id: http://core.svn.wordpress.org/trunk@53427 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-list-table.php

@@ -1108,7 +1108,10 @@ class WP_List_Table {
 	 */
 	protected function get_column_info() {
 		// $_column_headers is already set / cached.
-		if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) ) {
+		if (
+			isset( $this->_column_headers ) &&
+			is_array( $this->_column_headers )
+		) {
 			/*
 			 * Backward compatibility for `$_column_headers` format prior to WordPress 4.3.
 			 *
@@ -1116,12 +1119,18 @@ class WP_List_Table {
 			 * column headers property. This ensures the primary column name is included
 			 * in plugins setting the property directly in the three item format.
 			 */
+			if ( 4 === count( $this->_column_headers ) ) {
+				return $this->_column_headers;
+			}
+
 			$column_headers = array( array(), array(), array(), $this->get_primary_column_name() );
 			foreach ( $this->_column_headers as $key => $value ) {
 				$column_headers[ $key ] = $value;
 			}
 
-			return $column_headers;
+			$this->_column_headers = $column_headers;
+
+			return $this->_column_headers;
 		}
 
 		$columns = get_column_headers( $this->screen );

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53867';
+$wp_version = '6.1-alpha-53868';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.