Performance Plugins from WPIntense
WP Intense has three plugins that are performance focused and are for medium to large sites. You won't see much improvement on a small site. The main plugin is Scalability Pro which adds indexes to the WordPress database and removes or tweaks some default WordPress query options to make them more performant. Each feature has a toggle. The plugin is tested on a WooCommerce store with other a million products. Super Speedy Search is a high performance native WordPress search plugin, no third party server connection required. Super Speedy Filters is a filtering plugin that applies the filters to the database queries for optimal speed, unlike some which filter on page in the browser. Each plugin comes with an unlimited site, lifetime option.