title: Python asyncio runs slower
body: <p>I am new to Python and parallel execution and asyncio. Am I doing this incorrectly? My code runs slower (or at best equal) to the time it takes the scrip to run in a traditional manner, without asyncio.</p>
  
  <pre><code>import asyncio, os, time, pandas as pd
  start_time = time.time()
  
  async def main():
      coroutines = list()
      for root, dirs, files in os.walk('.', topdown=True):
          for file in files:
              coroutines.append(cleaner(file))
          await asyncio.gather(*coroutines)
  
  async def cleaner(file):
   df = pd.read_csv(file, sep='\n', header=None, engine='python', quoting=3)
   df = df[0].str.strip(' \t"').str.split('[,|;: \t]+', 1, expand=True).rename(columns={0: 'email', 1: 'data'}) 
   df[['email', 'data']].to_csv('x1', sep=':', index=False, header=False, mode='a', compression='gzip')
  
  
  asyncio.run(main())
  print("--- %s seconds ---" % (time.time() - start_time))
  </code></pre>