QuickBooks Online Slow Issue when An outdated version of the QuickBooks application, your computer doesn't meet the system requirement, the application may run slowly due to damaged or missing QBWUSER.INI File or Damaged Windows operating system can also slow the performances. If you still struggle to fix QuickBooks Online Slow Issue, Read through the article to cover the steps listed and understand how to fix QuickBooks Online Slow Issue or call the QB team on +1 800-579-9430.