How to speed up delete

Hello,
I was wondering if there is any way to speed up deletes on this table
(see details below)?
I am running few of these deletes (could become many more) inside a
transaction and each one takes allmost a second to complete.
Is it because of the foreign key constraint, or is it something else?

Thanks!

                                      Table "public.contacts"
    Column    |          Type          |
Modifiers
-------------+------------------------
+----------------------------------------------------------
id          | integer                | not null default nextval
('public.contacts_id_seq'::text)
record      | integer                |
type        | integer                |
value       | character varying(128) |
description | character varying(255) |
priority    | integer                |
itescotype  | integer                |
original    | integer                |
Indexes:
     "contacts_pkey" PRIMARY KEY, btree (id)
     "contacts_record_idx" btree (record)
Foreign-key constraints:
     "contacts_original_fkey" FOREIGN KEY (original) REFERENCES
contacts(id)

dev=# select count(id) from contacts;
count
--------
984834
(1 row)


dev=# explain analyze DELETE FROM contacts WHERE id = 985458;
                                                        QUERY PLAN
------------------------------------------------------------------------
------------------------------------------------
Index Scan using contacts_pkey on contacts  (cost=0.00..3.01 rows=1
width=6) (actual time=0.043..0.049 rows=1 loops=1)
    Index Cond: (id = 985458)
Total runtime: 840.481 ms
(3 rows)