I've got a silly question about performance

I'm still getting the hang of some of the finer points of creating queries in PostGIS, as is probably obvious with my last post.

I've two tables, parcel2 that is a collection of parcels in a county and a table election, which is a table of voting precincts in the same county. I'd like to select all of the parcels in each precinct.

I have this query:

select precinct, sit_st_num, sit_st_dir, sit_st_nam, sit_st_typ, city_code from election, parcel2 where ST_contains(election.the_geom, ST_pointonsurface(parcel2.wkb_geometry));

This gets the job done, but it's very slow. What can I do to speed this up?

Eric