Bursts of GHz repetition rate pulses can significantly increase the ablation efficiency of femtosecond laser material processing.. Ablation by GHz repetition rate bursts of femtosecond pulses is a multi-step process, consisting of a first thermal incubation phase, followed by a highly efficient ablation phase. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the ablation efficiency can be highly enhanced. Long bursts, comprising tens to hundreds of pulses, are required to take full advantage of the increase in ablation efficiency.