record from plpgsql function performance

Hello,

I have some simple function. The returned data set is generated based on
view (dynamic - can be changed on daily basis).
So the function was defined this way:

1. returns setof some_view as ...
2. inside the function I'm generating dynamic SQL into v_sql variable.
3. return query execute v_sql

Everything works fine if I'm running single function, like:
select * from function (param1, param2)
I'm getting the delimited fields in desired order.

But if I want to run the function in inline mode, like:
select function(param1, param2) from some_table;
so the returned datatype is record.

To return multiple fields, I'm trying to use:
select (function(param1, param2)).* from some_table;
But this operation has a huge performance impact, IMHO runtime multiplied
by number of columns - the function is executed for each column separately.
In my case normal inline run is about 2 seconds for 300-400 records, but
with ().* it's increased to 90-120 seconds.

Thank you in advance if you can suggest me the better way.

BR,
Alexander Shereshevsky