It used to be customary to stick around for five or ten minutes after Mass, to make prayers of thanks for Communion.
You can still do this. That gives you more time than just the space between receiving Communion and the priest sitting down again. (It also gets all the other cars out of your way, so you can zoom right out of the parking lot!)
Yes, this!
At the FSSP parish I attend occasionally, there might be a small handful of people that walk out during/after the closing hymn, but almost literally everyone stays after to make their thanksgiving - it is so beautiful to see and be a part of!
Unfortunately, not many people do that in Catholic parishes today. Something I notice in my parish nearly every single weekend Mass, really kind of saddens me: I am the organist, and (less than) five minutes after I have finished the closing hymn and put my books and organ shoes away, the Church is almost literally empty, and the lights have been shut off. This past Sunday I was literally the only one left after five minutes. I guess on one hand, if you’re praying your thanksgiving after Mass, and everyone is gone within five minutes, that means it won’t be noisy for very long in the Church!
However, if you go to a parish which gets really noisy after Mass, and you wish to pray your thanksgiving after Mass, I don’t think it would be unreasonable of you to ask your pastor to make an announcement to keep the noise down after Mass (and before, if that’s a problem). Because then, in my experience at least, I can still say my prayers and thanksgiving for receiving our Lord, but it can be so much harder to concentrate if there are more than a few people taking in something more than a whisper.
OK, sorry, I kind of got on a roll there…but anyway, I highly recommend staying an extra few minutes after Mass to make a thanksgiving, especially if it is too distracting for you to do it right after Communion. On one hand, it is good to try to improve your concentration at that time you actually receive our Lord and right after, but on the other hand, and in the meantime, making a thanksgiving after Mass is a good habit to get into.