Find similar records (compare tsvectors)

Hello,
I had a database with articles or attachment stored in bytea format.I also had a trigger: it insert/update the tsv column when a record is added/updated.The tsv column had a GIN index.With this setting, I can do very fast keyword search on the tsv.
Suppose I had a specific record (id=100000).How to list similar records based on ranking?In that case, I had to compare a tsvector with another tsvector.
I had this SQL which make the original tsv as a text and then to tsquery, Then I can compare a tsv and a tsquery.
SELECT ts_rank(i.tsv, replace(strip(original.tsv)::text, ' ', '|')::tsquery) as similarity, i.company, i.industry, i.post_timestamp, i.id FROM items i, (SELECT tsv, id FROM items WHERE id=100000) AS original WHERE i.id != original.id ORDER BY similarity;
items table:id bigint
company varchar
industry varchardescription varcharpost_timestamp timestampattachment bytea
tsv tsvector

The problem is that this is very slow.Any comment?
Thank and regards,Patrick