create table TEST (
  id number not null,
  td date not null,
  name varchar2(1000) not null
);
/
create or replace package pk_bulk_insert
as
  type
    t_bulk_rec is record (
      id number,
      td date,
      name varchar2(1000)
    );
  type
    t_bulk_data is table of t_bulk_rec;
  procedure Init;
  procedure Add(id number, td date, name varchar2);
  procedure Commit;
end pk_bulk_insert;
/
create or replace package body pk_bulk_insert
as
  MAX_BUFFER_SIZE constant binary_integer:=100;
  empty_data t_bulk_data:=t_bulk_data();
  bulk_data t_bulk_data;

  procedure Init
  is
  begin
    bulk_data:=empty_data;
  end;

  procedure InsertData
  is
  begin
    forall idx in bulk_data.first..bulk_data.last
      insert into TEST (id, td, name)
      values (
        bulk_data(idx).id,
        bulk_data(idx).td,
        bulk_data(idx).name
      );
    bulk_data:=empty_data;
  end;

  procedure Add(id number, td date, name varchar2)
  is
  begin
    if bulk_data.count>=MAX_BUFFER_SIZE then
      InsertData;
    end if;
    bulk_data.extend;
    bulk_data(bulk_data.count).id:=id;
    bulk_data(bulk_data.count).td:=td;
    bulk_data(bulk_data.count).name:=name;
  end;

  procedure Commit
  is
  begin
    if bulk_data.count>0 then
      InsertData;
    end if;
    commit;
  end;
end pk_bulk_insert;
/

public class Program
{
  public static void Main(string[] args)
    => BenchmarkRunner.Run<Program>();

  string _bulkSql;
  string _directSql;
  [GlobalSetup]
  public void CreateScipts()
  {
    var bulkBuilder = new StringBuilder();
    var directBuilder = new StringBuilder();
    bulkBuilder.AppendLine("begin").AppendLine("execute immediate 'truncate table TEST';").AppendLine("pk_bulk_insert.Init;");
    directBuilder.AppendLine("begin").AppendLine("execute immediate 'truncate table TEST';");
    for(var i=0;i<1000;i++)
    {
      bulkBuilder.AppendLine($"pk_bulk_insert.Add({i}, sysdate+{i}, '{(char)(i%26+65)}');");
      directBuilder.AppendLine($"insert into TEST (id, td, name) values ({i}, sysdate+{i}, '{(char) (i % 26 + 65)}');");
    }
    bulkBuilder.AppendLine("pk_bulk_insert.Commit;").AppendLine("end;");
    directBuilder.AppendLine("commit;").AppendLine("end;");
    _bulkSql = bulkBuilder.ToString();
    _directSql = directBuilder.ToString();
  }

  [Benchmark]
  public void DirectInsert()
  {
    using(var cnn = new OracleConnection(<.....>))
    using(var cmd = new OracleCommand(_directSql, cnn))
    {
      cnn.Open();
      cmd.ExecuteNonQuery();
    }
  }

  [Benchmark]
  public void BulkInsert()
  {
    using(var cnn = new OracleConnection(<.....>))
    using(var cmd = new OracleCommand(_bulkSql, cnn))
    {
      cnn.Open();
      cmd.ExecuteNonQuery();
    }
  }
}

// * Summary *

BenchmarkDotNet=v0.12.0, OS=Windows 7 SP1 (6.1.7601.0)
Intel Core i5-3470 CPU 3.20GHz (Ivy Bridge), 1 CPU, 4 logical and 4 physical cores
Frequency=3117998 Hz, Resolution=320.7186 ns, Timer=TSC
  [Host]     : .NET Framework 4.8 (4.8.3928.0), X64 RyuJIT
  DefaultJob : .NET Framework 4.8 (4.8.3928.0), X64 RyuJIT


|       Method |      Mean |     Error |     StdDev |
|------------- |----------:|----------:|-----------:|
| DirectInsert | 947.81 ms | 57.476 ms | 168.568 ms |
|   BulkInsert |  52.54 ms |  2.425 ms |   7.151 ms |