I have an accelerated search that runs really quickly in a search window, about 3 seconds.
When using the exact same search on a dashboard, it takes about 20 seconds to show up, and when I check the job inspector, I still have the same 3 seconds os exec_time.
What causes this major difference in behaviour?
As a general case, that usually is data transit time and render time for the browser. How much data is being returned?
Did you try and get the same wait time in other browsers as well?