This new query of mine pegs beta4, it doesn't return and CPU is at 100%:
select l.id_location,l.name,
a.city
from location l, address a, show_date x, show s, show s2
where (l.id_address = a.id_address
and x.id_location = l.id_location
and s.id_show = x.id_show
and s2.show_type = s.show_type and s2.id_show = 305)
or l.id_location = 172;
The tables are not big, at most a few hundred elements each, if that.
Maybe the query itself is flawed, I haven't tried it on other versions
of postgres.