I have a pharos 500 unit (a little more sensitive than yours). The first startup at a specific spot can usually be very quickly. But in some situations and specific spots, the startup can be very very long. I think that this is caused when the signal is weak i guess. Sometime, just moving position sligthly, and the link time is becoming a little shorter. I have seen 15, 20 mn (and even more) in extreme cases like inside my home to acquire 4 satellites to get a usable link. But at the same difficult spot (i guess it depends about the external temperature conditions?), sometimes it could even not link at all after an hour... In these hard conditions, gps location could be very inaccurate of what i have seen, and the gps lock is lost easily...
Using the same unit in my car facing the sky and it will lock in 1mn (max 2) in most of the cases everywhere, and it is working pretty well...
I suggest you do some tests with another nema tools. Install gpsdiag free tools from the following link:
http://www.laptopgpsworld.com/707-interesting-free-nmea-gps-tools
Then you will have a software that capture NMEA sentences, and displays the signal level of each satellites and the number of them, until you get a stable links. When the link is unstable, you will see in gpsdiag that the used satellites are often changing, or the signal is weak, and that you are using barely 4 satellite with varying signals a lot. Until the gps location (lat/lon) is locked and stable and match your real position. You will also see why the gps lock is lost often in these hard conditions. This will help to see why
Streets & Trips behavior is like that.
Suggestion: always use the usb extension cord to plug the unit in your computer...