procedure takes much more time than its query statement

Hi there,

I have the function:
CREATE OR REPLACE FUNCTION "Test"( ... )
RETURNS SETOF record AS
$BODY$
BEGIN
RETURN QUERY
SELECT ...;
END;
$BODY$
LANGUAGE 'plpgsql' STABLE

The function call takes about 5 minute to proceed, but using directly its
query statement, after replacing the arguments with the same values, it
takes just 5 seconds !

I repeat the test several times and the duration is the same.

What is wrong ?

Please note Postgresql version is "PostgreSQL 8.3.5, compiled by Visual C++
build 1400". I used ANALYZE, and my query / function returns about 150 rows.
I made the tests in pgAdmin query windows.

TIA,
Sabin