WooCommerce 2.4 made some performance improvements to the variable product interface. There’s an overview of the changes here: Improving the Variations Interface in 2.4
Where this helps most is in the case of products which have many variations – unfortunately, in some cases this may hinder re-ordering the variations due to the pagination. It is possible to increase the number of variations displayed per-page by using the WooCommerce provided filter named woocommerce_admin_meta_boxes_variations_per_page – the snippet below will set the number of variations displayed to 50 – you can edit it as needed. Please be aware that this may have a negative impact on server performance and the loading time of the product edit screen.
Not sure what to do with code snippets? See What Do I Do With These Code Snippets?