Queries using GIN index on f_unaccent() seem slow?
I have seen GIN indexes to generally perform much faster than GiST for these queries. Try this index instead:

CREATE INDEX price_item_occurrence_name_trgm_gin idx ON price_item_occurrence
USING GIN (f_unaccent(name) gin_trgm_ops);


Related:


Does PostgreSQL support “accent insensitive” collations?
Using ILIKE with unaccent and with only right end wildcard
How is LIKE implemented?
Pattern matching with LIKE, SIMILAR TO or regular expressions in PostgreSQL
Trigram index for for ILIKE patterns not working as expected


All the basic advice for performance optimization applies. For starters, your table needs to be VACUUMed and ANALYZEd enough to be fast.


Configuring PostgreSQL for read performance