Does whether this question is considered rude depend on the culture or country? Could it be rude in one culture but normal in another?

This is a claim of fact because it is something that can be proven through research and evidence. It is arguable because saying that caffeine “boosts performance” is very general. For example, I am from San Lucas Tolimán, Guatemala, where coffee is very common and people drink it at different times of the day, even at night. Since coming to the United States, I have often heard people say that coffee helps when you are tired or need more energy. This makes me question what “boosts performance” really means and whether it works the same for everyone.