50 Balls needed for Kevin O'Brien for his century against England in 2011, the fastest in men's ODI World Cup until the 2023 edition. His record was bettered twice in the tournament - first by Aiden Markram with a 49-ball hundred against Sri Lanka, and then by Glenn Maxwell, who got a century off 40 balls at the same venue against Netherlands. Six of the top ten fastest ODI World Cup hundreds have come in this edition itself.
That's the most astonishing part of this World Cup: the absolute ferocity of the centurions. Imagine, if England didn't implode in this World Cup, we would seen even more centuries from their formidable batsmen.