title: VS Code - Rename symbol too slow for Python
body: <p>I'm having this refactoring issue where I try to rename a function through the option "Rename symbol", but it will take a long time. There's a "progress bar" moving endlessly below the document tab. It is taking around 5 min to do the renaming (also with variable names).</p>
  
  <p>Is this a normal behaviour? I have about 10 python files in the same folder of around ~100 lines. BUT, I have a data folder (belonging to the project) with some 100,000 txt files (which is ignored by git, btw). Are this documents also taken into account? Is there a way to only rename in current file?</p>
  
  <p>VS Code version: 1.25.0
  Python extension: 2018.6.0</p>
  
  <p>Thanks, Rafa</p>