Is the time period 622-733 (111 years) a short or long period for an empire to grow to several times its original size?

111 years is a short period for an empire to grow several times its original size. Most empires throughout history have expanded their frontiers to the point of growing several times their original size only after centuries and many conflicts with other political entities.

The period 622-733 saw the expansion of an empire that grow very rapidly: the Islamic Empire. It started in 622 under the leadership of the Prophet Muhammad, who conquered the entire Arabian Peninsula. It continued growing after his death in 632, under the rule of the Caliphs who conquered the Persian Sassanian Empire and many territories of the Byzantine Empire in the Middle East and Egypt. The Omayyad Caliphate established in 661 conquered the rest of North-Africa and the Iberian peninsula in the west and got to the border of India to the East. All these territories were conquered in the lapse of a century, which represents a very fast expansion based on the power of military strategy and religious faith.

b. parliament was weaker than the monarchy.