Complex sentence: The 1988 race was a very hot race, and the circuit broke up very badly (as it often did during races, but the track disintegration was worse that year) due to the intense heat and humidity.
Split into simpler sentences: The 1988 race was a very hot race, and the circuit broke up very badly. Such track problems often occurred, but the track disintegration was worse that year due to the intense heat and humidity.