Why is there a comma in the this question? Does Polish use the comma differently?
Yes, Polish uses a comma whenever it introduces another clause. That is also why Polish people often try to put a comma before 'that' ;)
In English we often drop the 'that' knowing that it is still there. I think Polish has to keep it
If you are reading aloud or something then yes, sometimes. If you are just speaking, not so much.
I would say that even when speaking it is there, just that…ugh… What exactly is 'a pause' is very fluid(especially with regards to how long it lasts) and differs from speaker to speaker. ;)
At least, for me(when not reading, but just saying these), „Ona mówi” in „Ona mówi, że jestem stary” and „Ona mówi” in „Ona mówi: «jestem stary»” do not last exactly the same amount of time(still, it feels like the difference is measured in milliseconds :P).