text: Title: Speed up processing of VCFs when opening the contacts menu
  Body: Opening the contacts menu results for me to 627 calls to `Sabre\VObject\Parser\MimeDir::readLine` which takes alone around 0.75 seconds.
  
  Ref https://blackfire.io/profiles/2a140454-bfeb-4241-90a3-a9c8012f81e2/graph