acp-editing-bulk-editable_rows_per_iteration.php

<?php

/**
 * Change the amount of items being prepared per batch process for Bulk Edit.
 * This process is done before the actual processing finds place.
 */

/**
 * Prepare less items if you experiencing performance issues or time out issues
 *
 * @param int $amount Default is `2000`
 */
function acp_editing_bulk_less_items_per_iteration($amount)
{
    return 100; // Default is 2000
}

add_filter('acp/editing/bulk/editable_rows_per_iteration', 'acp_editing_bulk_less_items_per_iteration');