Before revision:  It does not introduce an overhead, and FastPitch retains the favorable, fully-parallel Transformer architecture of FastSpeech with a similar speed of mel-scale spectrogram synthesis , orders of magnitude faster than real-time  .
After revision:  It does not introduce an overhead, and FastPitch retains the favorable, fully-parallel Transformer architecture of FastSpeech with a similar speed of mel-scale spectrogram synthesis , orders of magnitude faster than real-time factor for mel-spectrogram synthesis of a typical utterance .