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, no 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.

• Sorting
• 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.

"Commerce": {
  "CatalogOptions": {
    "SimplifiedCatalogListingThreshold ": 2000

If not set, a default value of 2000 items per category is used.