>Someone could tell me if the numbers of tables in a database
>has an impact on access time. By example, when I use modify
>database command, it takes too much time. Also, why the remove
>table command takes so much time (up to 10 or 15 minutes by table)?

Two things I would look at:

1) The size of the DBC. Have you packed it recently, might it contain a lot of deleted records?

2) Open it EXCLUSIVE if at all possible - that makes a large performance difference compared to opening SHARED.