contrib/fulltextindex

Hello!

i've got a question on my problem..
i'm using contrib/fulltextindex to index my tables to do a fulltext search
but i'm using a non-default locale settings on my database.
i found out that if the locale is default 'C' then fulltextindex tables are
scanned very fast using btree indices. for sure, i'm using prefix match
(string ~ '^blabla') which is supposed to scan the table in this way.. so
it's ok!
but if i change to different locale (i.e. sk_SK or cs_CZ) the fti table is
scanned sequentially and it's very slow.. so, the more words are there in my
fti table and the more more words i'm trying to search at once using table
join the slower is the search..

so my question is.. is this a bug or the prefix match has no support to
perform a table scan using indices under non-default locale?
please, give me a hint..

regards

Tomas Lehuta