text: Title: [Feature request] Speed up voice cloning from the same speaker
  Body: <!-- Welcome to the 🐸TTS project!
  We are excited to see your interest, and appreciate your support! --->
  **🚀 Feature Description**
  Thanks to the project.
  We had a try and the result is pretty good.
  However, there is one major issue, the voice cloning speed is slow, especially inference by CPU.
  We might need to generate the voice several times from the same speaker, could we speed up the process?
  <!--A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] -->
  
  **Solution**
  Here is how we use the code:
  ```
   # Init TTS
      tts = TTS("tts_models/multilingual/multi-dataset/xtts_v2").to(device)
  
      # Text to speech to a file
      tts.tts_to_file(text=words, language="zh-cn", file_path=out, speaker_wav="data/audio/sun1.wav")
  ```
  Since we might need to clone the same speaker, and generate the voice for several times, is is possible to speed up the process?
  Could we export some middle results or fine tuned model, and reused or reloaded the model next time?
  We might expect the voice generate speed could be as fast as using the single model.
  
  <!-- A clear and concise description of what you want to happen. -->
  
  **Alternative Solutions**
  
  <!-- A clear and concise description of any alternative solutions or features you've considered. -->
  
  **Additional context**
  
  <!-- Add any other context or screenshots about the feature request here. -->
  