Performance of SQL Function versus View

Do you see any performance difference between the following approaches? The assumption is that most of the rows in the query will be requested often enough.

1.       SQL function.

CREATE OR REPLACE FUNCTION X(IN a_id uuid, IN b_id uuid)

 RETURNS int

  STABLE

AS $$

  SELECT count(1)

     FROM A, B

     WHERE a_join_id = b_join_id

       AND A.a_id  = a_id

       AND B.b_id = b_id;

$$ LANGUAGE SQL;

SELECT X(a_id, b_id);

2.       View.

CREATE OR REPLACE VIEW X AS

  SELECT a_id, b_id, count(1) cnt

     FROM A, B

     WHERE a_join_id = b_join_id

GROUP BY (a_id, b_id)

SELECT cnt FROM  X WHERE X.a_id = a_id and X.B_id = b_id;

Thank you,

Igor