slow UNIONing

I experienced that UNIONs in 7.1.1 are rather slow:

tir=# explain (select nev from cikk) union (select tevekenyseg from log);
NOTICE:  QUERY PLAN:

Unique  (cost=667.63..687.18 rows=782 width=12) ->  Sort  (cost=667.63..667.63 rows=7817 width=12)       ->  Append
(cost=0.00..162.17rows=7817 width=12)             ->  Subquery Scan *SELECT* 1  (cost=0.00..28.16 rows=1316 width=12)
               ->  Seq Scan on cikk  (cost=0.00..28.16 rows=1316 width=12)             ->  Subquery Scan *SELECT* 2
(cost=0.00..134.01rows=6501 width=12)                   ->  Seq Scan on log  (cost=0.00..134.01 rows=6501 width=12)
 

Of course a simple SELECT is fast:

tir=# explain select nev from cikk;
NOTICE:  QUERY PLAN:

Seq Scan on cikk  (cost=0.00..28.16 rows=1316 width=12)


For me it seems to be slow due to the sorting. Is this right?
Is this normal at all? Is it possible to make it faster?

TIA, Zoltan

--                         Kov\'acs, Zolt\'an                        kovacsz@pc10.radnoti-szeged.sulinet.hu
          http://www.math.u-szeged.hu/~kovzol                        ftp://pc10.radnoti-szeged.sulinet.hu/home/kovacsz