What are the limitations of SimpleQuiz concerning number of participants?

Let us assume, we would invite some thousand people to participate in a survey or in a quiz. All their results have to be stored in the database. But databases do have limitations...  and perhaps SimpleQuiz has limitations also.
How would you describe these limitations, which we will experience, when using SimpleQuiz to this extent?

Thank you very much for your ultra quick reply!
My question was not hypothetical, because I know some people, who are in search for an affordable tool for consensuasion / surveys with large number of participants. Such a consensuation typically contains only a few items / proposals so that the number of participants and results will not decrease too much.

I am happy to see more and more, how valuable your SimpleQuiz really is and what potentials it brings!