Long delay finding satellites could be caused by the fact you don't use your Garmin all the time. I mean if you turned it off in location A then moved to location B and turned it on you will experience problems acquring the sattelites. I think not Garmin only, majority of the devices do the same.
The reason behind might be the SW algorithms. Your device remembers the last location. The statellites are hanging on geostationary orbit, i.e. appear motionless, at a fixed position in the sky, to ground observers. So when you move with the GPS turned on, the move is slow and it's easy for GPS to follow your movement. But when you move with GPS Off, "the brains" of the GPS receiver get cleared and it has to find 5-6 sattelites from scratch to give you an exact location
After my trip in Europe: Sweden-Germany-Austria-Slovenia-Croatia and back I can report the SW quality is very good. I remember one crash only but it's OK I think.
What I did not like: sometimes, seldom, it looks like when one map had finished and another peace is going to be loaded, the sector on the map become grey (not updated) and if you are about to perform a maneuver, but can't see the map you don't become happy
I have experienced the same, and tried everything to fix it, sometimes it froze, sometimes it took 10-15 minutes.
I tried everything and anything, and eventually decided it must be a hardware issue that I cant fix.
I have the similar experience. Every time I drive out from the basement carpark and the unit continue searching the satellite even I am outside the building.
It would be good option to turn off your unit or just restart new route in order to re-get new satellite signal.
I've had this same problem and have previously done exactly what life.by said. Leave it off until exiting the underground garage and then it boots right up with no trouble. I was in an area of Northwestern Massachusetts 2 weeks ago and had it occur in the mountains. Zero cell phone signal (thanks Verizon) & good 'ol Garmin couldn't get any signal & kept saying "Lost satellite reception". I guess every device has its limitations but try to turn it on well after you've left an area where signal is questionable. Do you get cell phone signal in these areas? No? That may help you identify the mystery...
I do find the 3790 very annoyingly poor in reception. Especially when you need to drive in cloudy days or in the city where there are more tall building. It would easily lose satellite reception. This is not the case with my old 760. I continue using the 3790 simply for the lane guidance function. Otherwise, I would be happier using my old 760.