According to the solo student pilot, he was practicing touch-and-go takeoffs and landings. On the third approach as the pilot turned on final, the tower controller asked him to complete a full stop landing due to an increased number of aircraft in the airport area. The landing and roll out were normal, but when the pilot attempted to turn off of the runway onto a taxiway, the airplane was traveling too fast. He applied the brakes, yet the airplane proceeded off the side of the taxiway and impacted a pole, resulting in substantial damage to the left wing and fuselage. During an examination of the wreckage, a Federal Aviation Administration inspector found no anomalies with the airplane that may have contributed to the accident.