If I select a facet and let the page load, all other facets are not displayed and only the attribute (and its parents in the case of categories) that is selected is displayed (checked indicating that it is selected. This is expected and desired behavior.
However, if the user quickly checks a bunch of facets then the page loads them all one at a time. If even just a few are selected, while this loading is happening the user cannot use the page as they have to wait until everything loads to do so.
It would be ideal that when the user selects the first facet that all others are grayed out preventing the above behavior. Maybe this requires a setting in the backend? Not sure.