I have run the following tests to Fill a DataSet:

1) SqlDataAdapter.Fill(dsNames)
2) SqlDataAdapter.Fill(dsNames, "Names")

Using our database and table, the first one takes 15 seconds to Fill while
the second one takes 4. Why does the time dramatically decrease when I
add the second parameter?

I stumbled on this by mistake when a colleague and I were access the same
table with the same query. His took 15 seconds to Fill while mine took
5. The only difference is the missing second parameter in his Fill.