TimesTen : Performance Issue With Execute Immediate Vs. Embedded Sql

Hello, .
I am testing a PL/SQL loop doing inserts and it seems that embedded sql is a lot faster
than using execute immediate, sample code below.  Is this expected behavior?
.
Execute Immediate:
.
declare
 type t_row_collection is table of t1%rowtype index by binary_integer;
 t_rows t_row_collection;
 sql_str varchar(50); 
begin
 select * bulk collect into t_rows from t1;
 for j in t_rows.first .. t_rows.last loop
  sql_str := 'insert into t2 values (' || t_rows(j).f1 || ', ''' || t_rows(j).f2 || ''');';
  execute immediate sql_str; 
  commit;
 end loop;