Why does it take so long for a program like Mapdroid to use the GPS to track you on a map I was in London last week (which is outside my country, so I did not use roaming to connect to the internet to be able to use the maps application from Google). In stead , I used Mapdroid to find my way around the center there.

Mapdroid, for those who don't know this program, lets you download maps and than use them without data connection. The only thing you need to do is turn on the GPS.

This works great apart for the fact that it can take between 5 and 10 minutes for the program to mark you location. If it does, it can track you fine , and it keeps tracking you on the map.

But I am just wondering why it takes so long before Mapdroid knows where you are.

Is it a hardware thing (I have a Samsung Galaxy S phone running Froyo).
This shows the difference between AGPS and GPS. AGPS (Assisted GPS) uses a small amount of mobile data to establish a rough location fix (about 1km-100m accuracy) based on the cell towers near you. This gives a faster initial location fix than just GPS. Since you had roaming disabled, AGPS wasn't available and getting a location fix on just GPS can take a while, especially on some firmware versions of the Galaxy S.