Ok, you have to remember that a 2 stroke fires two times as often as a 4 stroke, so you should get twice the power out of a similar diplacement 4 stroke. More power is geared equally will be faster, does not matter if it is dirt, paved, snow, you name it. 2 strokes do have draw backs, they are noisy, they usually need special oil added, they pollute pretty bad and are not nearly as efficient as modern 4 strokes.
They still race 2 stroke 125 and 250 gp bikes. If you are lucky Speed will show these races before MotoGP, but our stupid american market thinks that us viewers will not have any interest if it isn't a liter bike. Not very long ago, MotoGP used to be 500GP with 500 CC two strokes which were every bit as fast as todays 1000CC 4strokes, only they were very hard to ride. With extreme power bands that went from flat to spike in no time. They changed the format to make the bikes more rideable and safefer along with other reasons.