When you're adding web parts to a web part page in SharePoint you first open the web part browser pane (eg. via 'Modify Shared Page' -> 'Add Web Parts' -> 'Browse'). At this point there is a long delay before the web part browser comes up. This is really annoying when you're designing a page and need to open this gallery frequently.
This delay is caused by SharePoint populating the Online Gallery by going to Microsoft's servers (btw, in the Web.config file you can change that to point to your own online gallery). In many deployments, however, the web parts in the Online Gallery are never used. The good news is that you can easily turn this off.
- Go to the SharePoint Central Administration site on the server.
- Click Configure virtual server settings and select the relevant virtual server.
- Click Manage security settings for Web Part Pages under Security Settings.
- Disable the Online Web Part Gallery and press OK.
Now try and add web parts to a web part page again and see how quick the web part browser opens up.