Once the databases have been selected in the Database Panel you'll notice that most of the properties in the grid appear with a yellow background; these properties are gathered using summarized information and will load very quickly.
Apart from speed, a compelling benefit of using summarized information is that properties for databases to which you have no access can still be displayed.
Some other properties will be grayed out when you initially select the databases because these properties do not have summarized information available.
In order to display them fully, you simply select their lines in the grid and click Edit > Load Complete Database Information (Ctrl + L).