The Performance Mode is a unique module that allows developers to optimize ACF metadata and enhance database load with two different methods: Ultra & Hybrid Engines.
The Hyrid Engine compress all field meta references (field_abcdef123456) and effectively cut in half Posts, Terms, Users & Options pages metadata. Based on years of experience with the Ultra Engine (formerly known as Single Meta), this alternative solution combines the best of both worlds.
It makes ACF on par with the native WordPress meta logic, without sacrificing any ACF feature, while maintaining compatibility with WP_Query and search plugins out-of-the box.
Formerly known as Single Meta, the Ultra Engine is a cutting-edge feature which drastically lighten the database load by compressing posts, terms, users and options pages metadata into a single row per object.
The benefits of this functionality are significant when dealing with complex Flexible Content/Repeater structures which might generate hundreds of metadata per post, bloating the database when saving/loading posts.