I didn't look at the workbook, because I can't open it (I get an error message)...but the fact that your Layout time is upwards of 20+ seconds tells me you're most likely plotting hundred-of-thousands to millions of marks on your dashboard. That takes time and is resource intensive. It is not a best practice.
Generally, the "expensive" part of executing a viz/dashboard is running the query - your query is executing quite quickly already, and most of the performance improvements between 8.x and 9 focus on making the queries go faster.
Most people don't render many, many marks on a viz because the results aren't useful to human beings - the average person can't "look" at that many things.