In case while creating the report if that report is having any input parameters then those input parameters value can be passed via the URL. In case if thats not passed the report/dashboard generally opens with the default values.
It seems some file JS CSS is not present on the server for which this is loading and taking lot of time. Can you open console of the browser and share a screenshot of that so that we can understand the issue and extend required help? Console can be opened in chrome by the shortcut “Ctrl + Shift + I”.