Strange join...maybe some improvements???

I have 3 tables:
CREATE TABLE orders
(
id int4 SERIAL,
id_ag int4,
id_modell int4 ->> this is linked to the modell.id
)

CREATE TABLE modell
(
id int4 SERIAL,
id_hersteller int4)

CREATE TABLE contactpartner
(
id int4 SERIAL,
id_ag int4, ->> this is linked to order.id_ag or modell.id_hersteller
id_user int4
).

I get a list of id_ag from the contactpartner which belongs to a user(AG_LIST). Then I have to selectselect/count all the data's from the order table that have the order.id_ag in the AG LIST or which have the modell.id_hersteller in the AG_LIST.

I have this query:

SELECT count(o.id) FROM orders o
INNER JOIN modell m ON m.id=o.id_modell
WHERE o.id_ag IN (SELECT id_ag FROM contactpartner cp WHERE id_user=15) OR m.id_hersteller IN (SELECT id_ag FROM contactpartner cp WHERE id_user=15)

Aggregate (cost=7828.60..7828.60 rows=1 width=4) (actual time=1145.150..1145.151 rows=1 loops=1)
-> Hash Join (cost=1689.64..7706.32 rows=48913 width=4) (actual time=153.059..1136.457 rows=9395 loops=1)
Hash Cond: ("outer".id_modell = "inner".id)
Join Filter: ((hashed subplan) OR (hashed subplan))
-> Seq Scan on orders o (cost=0.00..3129.17 rows=65217 width=12) (actual time=0.031..94.444 rows=65217 loops=1)
-> Hash (cost=1218.07..1218.07 rows=66607 width=8) (actual time=151.211..151.211 rows=0 loops=1)
-> Seq Scan on modell m (cost=0.00..1218.07 rows=66607 width=8) (actual time=0.044..87.154 rows=66607 loops=1)
SubPlan
-> Index Scan using contactpartner_id_user_idx on contactpartner cp (cost=0.00..6.02 rows=2 width=4) (actual time=0.010..0.018 rows=4 loops=1)
Index Cond: (id_user = 15)
-> Index Scan using contactpartner_id_user_idx on contactpartner cp (cost=0.00..6.02 rows=2 width=4) (actual time=0.092..0.116 rows=4 loops=1)
Index Cond: (id_user = 15)
Total runtime: 1145.689 ms

I tried also this one:

SELECT count(o.id) FROM orders o
INNER JOIN modell m ON m.id=o.id_modell
INNER JOIN contactpartner cp ON cp.id_user=15 AND (o.id_ag=cp.id_ag OR cp.id_ag=m.id_hersteller)

Aggregate (cost=11658.63..11658.63 rows=1 width=4) (actual time=1691.570..1691.570 rows=1 loops=1)
-> Nested Loop (cost=7752.40..11657.27 rows=542 width=4) (actual time=213.945..1683.515 rows=9416 loops=1)
Join Filter: (("inner".id_ag = "outer".id_ag) OR ("outer".id_ag = "inner".id_hersteller))
-> Index Scan using contactpartner_id_user_idx on contactpartner cp (cost=0.00..6.02 rows=2 width=4) (actual time=0.108..0.188 rows=4 loops=1)
Index Cond: (id_user = 15)
-> Materialize (cost=7752.40..8723.57 rows=65217 width=12) (actual time=37.586..352.620 rows=65217 loops=4)
-> Hash Join (cost=1677.59..7368.18 rows=65217 width=12) (actual time=150.220..1153.872 rows=65217 loops=1)
Hash Cond: ("outer".id_modell = "inner".id)
-> Seq Scan on orders o (cost=0.00..3129.17 rows=65217 width=12) (actual time=0.034..95.133 rows=65217 loops=1)
-> Hash (cost=1218.07..1218.07 rows=66607 width=8) (actual time=149.961..149.961 rows=0 loops=1)
-> Seq Scan on modell m (cost=0.00..1218.07 rows=66607 width=8) (actual time=0.032..86.378 rows=66607 loops=1)
Total runtime: 1696.253 ms

>>>>>>>> but this brings me some double information(the same o.id) in the situation in which the o.id_ag and m.id_hersteller are different, but still both in the AG_LIST.

Is there any way to speed up this query???

Regards,
Andy.