Performance Tuning on SQL's Over DB link

[PAVB]

Better for you to check Oracle documentation, nevertheless here is a clue...

alter session set timed_statistics = true;
alter session set sql_trace = true;
set autotrace on explain
alter session set events='10046 trace name context forever, level 8';
++ EXECUTE SQL ++
alter session set sql_trace = false;
alter session set timed_statistics = false;

I'm serious, check the documentation. If you don't do it we will know