Efficient way to get updated column names on an after update trigger

I've come up with the following trigger to extract all the column names which are updated when a table row update statement is executed...

but the problem is if there are more columns(atleast 100 cols), the performance/efficiency comes into concern

sample trigger code:

set define off;
create or replace TRIGGER TEST_TRIGG
AFTER UPDATE ON A_AAA
FOR EACH ROW
DECLARE
    mytable varchar2(32) := 'A_AAA';
    mycolumn varchar2(32);
    updatedcols varchar2(3000);

    cursor s1 (mytable varchar2) is 
        select column_name from user_tab_columns where table_name = mytable;
begin

        open s1 (mytable);

        loop
            fetch s1 into mycolumn;
            exit when s1%NOTFOUND;

            IF UPDATING( mycolumn ) THEN
                updatedcols := updatedcols || ',' || mycolumn;
            END IF;

        end loop;
        close s1;
        --do a few things with the list of updated columns
    dbms_output.put_line('updated cols ' || updatedcols);
end;
/

Is there any alternative way to get the list?

Maybe with v$ tables (v$transaction or anything similar)?