What happens if you connect using sqlplus and do this

On a laptop I am getting about 15,000 inserts per second. I would look
if the driver is set up correctly or if the C# code can be otherwise
optimized.

SQL> create table t (n number);

Table created.

Elapsed: 00:00:00.28
SQL> begin
  2    for i in 1 .. 100000 loop
  3      insert into t values (i);
  4    end loop;
  5  end;
  6  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:06.68
SQL> select 100000 / 6.68 inserts_per_sec from dual;

INSERTS_PER_SEC
---------------
     14970.0599

This is also using a loop construct which is about the slowest method
that can be used. If set based processing can be used then the rate
will go up further

SQL> insert into t
  2  select level n from dual
  3  connect by level <= 100000;

100000 rows created.

Elapsed: 00:00:04.85
SQL> select 100000 / 4.85 inserts_per_sec from dual;

INSERTS_PER_SEC
---------------
     20618.5567

This is on a pretty low powered, 4 year old windows laptop with 512 MB
of RAM and a vanilla install of 10g. So any half decent production box
should be able to kick sand in the face of these numbers.

--
MJB