Why is data retrieval so slow over network compared to locally?

Oracle 11gR2 11.2.0.3 Patch 21 on Windows 2008R2 x86_64  Both EE and SE

When I run the following test case within SQL Developer 4.x or in sqlplus at the command prompt, on the actual database server, then the response time to get all the rows is under 6s.

drop table bak_itest;
create table bak_itest (dummy varchar2(100));
alter table bak_itest add (dummy2 varchar2(100));  
alter table bak_itest add (dummy3 varchar2(100)); 
alter table bak_itest add (dummy4 varchar2(100));  
alter table bak_itest add (dummy5 varchar2(100));

begin
  for v_i in 1..100000 loop
     insert into bak_itest values(v_i,v_i,v_i,v_i,v_i);
  end loop;
  commit;
end;
/

select * from bak_itest;