query tuning

the following code is taking time 40 mins to complete. earlier it was completing in 5 mins

   begin

for c_invalid in (

select master_style

from ecomm_master_style m,

uda_item_lov u

where m.master_style = m.mau_style

and m.mau_style = u.item

and u.uda_id in (select uda_id from ecomm_master_style_udas)

                                             and exists (select 1 -- ecomm UDA must be on

from  uda_item_lov u2

where  u2.item = u.item

and u2.uda_id = ecomm_uda)

) loop

:rc := 2;

dbms_output.put_line(' ');

dbms_output.put_line('New master style ' || c_invalid.master_style