The cadenza is written to show the range, technical ability and style of the player. It should be played in a manner that will show off the individual player to the best advantage. All of the cadenza should not be played fast, but usually it should be begun very slowly and gradually played faster and louder until a climax is reached, which is often at a hold sign. The long series of notes of the cadenza should be divided in groups of threes or fours, leaving the odd notes as pick-up notes before playing the groups. Take your time and make your cadenza sound interesting.
Many performers seem to think the faster they play and sooner they finish the cadenza, the better.
This is a serious mistake. The same cadenza may be played by ten great soloists and each soloist may play it a different way, yet each rendition may be correct and effiecttive. Gradual contrast in speed and dynamics is important. If there is a trill to be played, it should begin very slowly and grow faster little by little until it reaches your utmost speed and this should seldom be a hurried process. If the cadenza is a very long one containing many hold signs.