Question: Does `dbms_output.put_line` decrease the performance in `plsql` code?

Answer: 
Yes, it's another piece of code that needs to be executed, but unless the output is actually turned on, I think the overhead is quite minimal.

Here's an AskTom question with more details: [Is there a performance impact for dbms\_output.put\_line statements left in packages?](http://asktom.oracle.com/pls/asktom/f?p=100:11:0%3a%3a%3a%3aP11_QUESTION_ID:1468572900346293780)
Using DMBS\_OUTPUT might also be the cause of the following error:

ORA-04036: PGA memory used by the instance exceeds PGA\_AGGREGATE\_LIMIT