Delphi Firebird speed problem

Hi,

I develop an application in Delphi 7 using a firebird database. I have a big problem with speed in a select statement that i use after i insert into a table some records.I insert records into the table and everything is ok with speed if i don't select anything after this and doesn't matter how many records i have into this table but when i select some data because i want to present them into a dbgrid and to take some totals into editboxes and i have more than 500 records the query takes more than 4 seconds to executed!!!
This table could be have thousands of records and now i have more than 100,000 records.

Here is an example of the source code:

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//here i insert records

ibquery2.SQL.Clear;
ibquery2.sql.Append('INSERT INTO table (var1,var2,var3) VALUES (test,test,test);
Ibquery2.ExecSQL;
ibtransaction1.Commit;

//here I select some data for the dbgrid and here starts the speed problem if I have many
//records into the table as i said before
//the query executed into 2 or 3 secs

ibquery2.sql.Text:='select id,pid,var1,var2,var3 from table where id=' + label5.Caption + ' order by id,pid ASC';
ibquery2.Open;


//and here the speed problem seems to be very big
//the query executed into 4 or 5 secs

ibquery4.SQL.Clear;
ibquery4.SQL.Text:='select sum(var1) from table where id=' +label5.Caption + ' AND level=1';
ibquery4.Open;

edit1.Text:=FormatFloat('#,##0.00',ibquery4.Fields[0].Value);
edit7.Text:=FormatFloat('#,##0.00',ibquery4.Fields[0].Value);

ibquery4.SQL.Clear;
ibquery4.SQL.Text:='select sum(var2) from table where id=' +label5.Caption + ' AND level=1';
ibquery4.Open;
edit2.Text:=FormatFloat('#,##0.00',ibquery4.Fields[0].Value);

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Help me about what i am doing wrong and i have these speed problems and what i have to do to fix this.

Thanks in advance.