It can be more than a few seconds - if you have a Profiler with a lot of content a large part of the database/transaction log might be force-scanned. I had cases where this was way more than 30 seconds. Also the underlying filesystem will re-check if it was not properly shutdown.
The last thing you want is data loss. The Profiler does the best it can, but better safe than sorry.
Just shut it down properly whenever you can.