Is your data static? Can you pre-process your date ranges into a new field? If so, and depending what kind of widgets you're using, the dashboard may be able to pull your data down using a stats query (much, much more efficient) rather than pulling down all 14k records.
If the data's static but you don't own it, could you summarize it into your own dataset? Or, if it's updated at regular intervals, maybe use a Notebook to summarize it automatically.