Thank you Wilfried for your reply,

I think the database would be a solution even it would be too large to create... I thought to another solution which I post so it could help someone else. (not tested yet).

The goal is to know if around a given location there are many roads or not... so I can modify the zoom level.

The steps should be:
- Create a random set of location around the given location (the number of the location should be found experimentally)
- Get the address for all of these location, without any search alghorithm, just search in the given point.
- The number of found valid addresses could be a measure of how many roads are in the around of the given location.

I'll let you know if this can work... and if this would be enough fast.

Bye!