yes, it's in air.
Currently OA (.52) makes 3 requests (delay between requests is about 3-5 secs) to get main page + events + fleets in movement. So, there is a difference between what OA shows and what is shown in Browser.
Currently I've boosted OA (.53), so it takes less then 1 second (like your browser) to get all information.
When you are attacked and a fleet arrives OA updates the fleet movements after 0.5-1 second + refresh time 0.5 second
If the enemy fleet arrives within 60 seconds, a boost mode in activated, means no delay between request : refresh time 0.5 second in order to detect the fleet and to start FS
Total : 2 seconds + make about 20 requests in boost mode (depends on connection : about 1-2 seconds) = 3-4 seconds to FS in case of ninja
P.S but it's only the theory, have to be tested in practice...
