You should model the catalog using category hierarchies to avoid having too many items in a category. Too many items in a category makes it difficult for the user to find an item using the catalog UI components. Also, the catalog UI may become slow, and handling the items can consume a large amount of system resources, on both the server and client side.
If a category contains more than a certain number of items (by default 2000), a simplified UI mode is used, disabling the following features to try to stay responsive.
Grouping variants into their parent products
Bundling/packaging items into a bundle/package
In simplified UI mode, a message appears in the catalog listing: **This category listing contains too many items. Some features were disabled to improve performance.**
To configure the simplified mode threshold, use the **SimplifiedCatalogListingThreshold **appSetting.
If not set, a default value of 2000 items per category is used.