Blocks are the boxes of content that can be displayed in regions (such as footer or sidebar) on your page. Depending on your themes regions you may have the ability to include blocks in your right,
Following are the steps to add an external link to menu in Drupal:
1. In the navigation menu click Administer -> Site Building -> Menus
2. Choose the menu you would like to add the external link to
Following are the few Tips to optimize and to increase the speed/performance of Drupal based website:
1. Uninstall unneeded modules.
2. Remove unnecessary content.
3. In admin/settings/performance change the Caching Mode to Normal.