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..162.17 rows=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..134.01 rows=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(at)pc10(dot)radnoti-szeged(dot)sulinet(dot)hu
http://www.math.u-szeged.hu/~kovzol
ftp://pc10.radnoti-szeged.sulinet.hu/home/kovacsz