Fastest Triple Hundreds in Test
Record of fastest triple hundreds (300) in test cricket is held by India's Virender Sehwag, as you can see in 3rd table below. note that most triple centuries were made in yesteryears when cricket stats didn't record the number of balls played but number of minutes batted by the batsmen. hence, cricketing world don't have the accurate figures for fastest triple centuries in test matches. Karun Nair's is, phenomenally for such a young cricketer, the fourth fastest triple century.
Fastest Triple century by innings