explain
select u.name, p.session_id, p.post_number, to_char(p.time,'Dy, Mon DD YYYY HH:MIam ET'), p.time
                        from
                                (
                                        select
                                                        p.poster_id,
                                                        p.session_id,
                                                        p.post_number,
                                                        p.time
                                                from chat_post p
                                                where
                                                                p.time = '1997-12-31 19:00:00-05'
                                                        and p.post_number > 71
                                                        -- narrow further the where clause
                                                        and
 exists (select 1 from chat_user u where u.id = p.poster_id and  ( u.lower_name = 'bacon' ))

                                                order by p.time
                                                limit 101
                                ) p,
                        chat_user u
                        where u.id = p.poster_id
                union all
                select u.name, p.session_id, p.post_number, to_char(p.time,'Dy, Mon DD YYYY HH:MIam ET'), p.time
                        from
                                (
                                        select
                                                        p.poster_id,
                                                        p.session_id,
                                                        p.post_number,
                                                        p.time
                                                from chat_post p
                                                where
                                                                p.time > '1997-12-31 19:00:00-05'
                                                        and
                                                                p.time <= '2002-11-08 19:00:00-05'
                                                        -- narrow further the where clause
                                                        and
 exists (select 1 from chat_user u where u.id = p.poster_id and  ( u.lower_name = 'bacon' ))

                                                order by p.time
                                                limit 101
                                ) p,
                        chat_user u
                        where u.id = p.poster_id
                order by time, post_number
                limit 101
;
