WordPress: Sample Code to debug slow DB queries when in WP-CLI

slow-db-queries.php

<?php

global $wpdb;

$wpdb->queries = [];

// Run some slow code here.

if ( ! empty( $wpdb->queries ) ) {

	// Convert to ms.
	$wpdb->queries = array_map(
		function( $q ) {
			$q[1] = $q[1] * 1000;
			return $q;
		},
		$wpdb->queries
	);

	usort( $wpdb->queries, function( $a, $b ) {
		return $a[1] - $b[1]; // Query time in seconds.
	});

	foreach ( $wpdb->queries as $q ) {
		\WP_CLI::line( $q[1] . ': ' . $q[0] );
	}
}