我想你自己已经回答了这个问题。另一个原因可能是NAS的硬盘驱动器速度慢（5.400 rpm），或者连接速度慢。

编辑：加快删除不需要的仪表板项目的速度。。。

<?php
/*
Plugin Name:    Dashboard-Widgets Removal Plugin
Plugin URI:     http://example.com
Description:    Disables admin UI dashboard widgets that you do not want
Author:         Franz Josef Kaiser
Author URI:     http://say-hello-code.com
Version:        0.1
License:        GPL v2 - http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
*/
/**
 * Disable unwanted Dashboard Admin UI Widgets
 */
function oxo_dashboard_widgets() {
    if ( !is_admin() ) 
        return;

    global $wp_meta_boxes;
    // Right Now - Comments, Posts, Pages at a glance
    # unset( $wp_meta_boxes[\'dashboard\'][\'normal\'][\'core\'][\'dashboard_right_now\'] );
    // Recent Comments
    # unset( $wp_meta_boxes[\'dashboard\'][\'normal\'][\'core\'][\'dashboard_recent_comments\'] );
    // Incoming Links
    # unset( $wp_meta_boxes[\'dashboard\'][\'normal\'][\'core\'][\'dashboard_incoming_links\'] );
    // Plugins - Popular, New and Recently updated Wordpress Plugins
    unset( $wp_meta_boxes[\'dashboard\'][\'normal\'][\'core\'][\'dashboard_plugins\'] );

    // Wordpress Development Blog Feed
    unset( $wp_meta_boxes[\'dashboard\'][\'side\'][\'core\'][\'dashboard_primary\'] );
    // Other Wordpress News Feed
    unset( $wp_meta_boxes[\'dashboard\'][\'side\'][\'core\'][\'dashboard_secondary\'] );
    // Quick Press Form
    # unset( $wp_meta_boxes[\'dashboard\'][\'side\'][\'core\'][\'dashboard_quick_press\'] );
    // Recent Drafts List
    unset( $wp_meta_boxes[\'dashboard\'][\'side\'][\'core\'][\'dashboard_recent_drafts\'] );
}
add_action( \'wp_dashboard_setup\', \'oxo_dashboard_widgets\' );
?>