Try setting both time and timing on in SQL*Plus by executing the following command:
set time on set timing on
Now, you will get the timing when executing your PL/SQL.
There are other ways to determing where a query is better one way than the other. You can use EXPLAIN plan on your SQL to see how the ORACLE compile will physically fetch records that are result of your query.
You can also use tkprof to see physical I/O associated with your SQL statements.