SQL> select * from v$version;

BANNER
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Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE    11.2.0.4.0      Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 - Production

SQL>
SQL> create table abc (
  2  id number,
  3  pad char(1000),
  4  constraint pk_abc primary key (id)
  5  ) organization index;

Table created.

SQL>
SQL> create table mnp (
  2  id number,
  3  pad char(1000),
  4  constraint pk_mnp primary key (id)
  5  );

Table created.

SQL>
SQL> create table xyz (
  2  id number,
  3  pad char(1000)
  4  );

Table created.

SQL>
SQL> set timing on
SQL>
SQL> begin
  2  for i in 1 .. 1000000 loop
  3  insert into abc (id, pad ) values (i * 1000000, lpad('X',1000,'X'));
  4  end loop;
  5  end;
  6  /

PL/SQL procedure successfully completed.

Elapsed: 00:01:40.61
SQL>
SQL> begin
  2  for i in 1 .. 1000000 loop
  3  insert into mnp (id, pad ) values (i * 1000000, lpad('X',1000,'X'));
  4  end loop;
  5  end;
  6  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:50.70
SQL>
SQL> begin
  2  for i in 1 .. 1000000 loop
  3  insert into xyz (id, pad ) values (i * 1000000, lpad('X',1000,'X'));
  4  end loop;
  5  end;
  6  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:32.55