My dashboard is running very slow and crashes my browser ever since I changed the text box to a multiselect box. This is because it was requested by a coworker who wants to put in multiple values at a time.
The search behind the multi value is schedulded once a week, and seems to be running very smoothly.
The problem really is the multi select, when you click on it and it drops down, it becomes super slow and you can't click or type anything, it will make your browser unresponsive.
This seems to be a problem related to the number of elements that populate the multiselect. In order to make it smoothly, you could try to add some filters in order to get less data into the multiselect element.