wp-config.php

Disable theme and plugins file edit:

define('DISALLOW_FILE_EDIT', true );

 

To limit the number of post revisions to 3:

define( 'WP_POST_REVISIONS', 3 );
/* That's all, stop editing! Happy blogging. */

Totally remove post revisions:

define('WP_POST_REVISIONS', false );

Updating WordPress

How to Disable Automatic Updates in WordPress

define('WP_AUTO_UPDATE_CORE', false);
define( 'AUTOMATIC_UPDATER_DISABLED', true );

Disable all the things, WordPress, themes, plugins and translations

define( 'AUTOMATIC_UPDATER_DISABLED', true ); 

Memory Limit

define( 'WP_MEMORY_LIMIT', '256M' );

Cron Jobs

define( 'DISABLE_WP_CRON', true ); // disable the built-in cron job system
define( 'ALTERNATE_WP_CRON', true ); // enable an alternate cron job system

WordPress Cache
Enabling the WordPress cache can improve the performance of your site by storing static copies of pages and posts. This can reduce the load on your server and make your site faster for users. To enable the cache, you can use the WP_CACHE constant in your wp-config.php file.

define( 'WP_CACHE', true );

WordPress Trash

define( 'EMPTY_TRASH_DAYS', 7 ); // permanently delete trashed items after 7 days
define( 'EMPTY_TRASH_DAYS', 0 ); // disable the trash

WordPress Auto-Save

define( 'AUTOSAVE_INTERVAL', 120 ); // auto-save every 120 seconds (2 minutes) 

WordPress Site URL and Home URL

define( 'WP_SITEURL', 'http://example.com/wp' );
define( 'WP_HOME', 'http://example.com' );

Custom Content Directory

define( 'WP_CONTENT_DIR', dirname( __FILE__ ) . '/custom-content-directory' );
define( 'WP_CONTENT_URL', 'http://example.com/custom-content-directory' );

Multisite Settings

define('WP_ALLOW_MULTISITE', true);
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'example.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);