Hi,I want to complain about slow working of my Quickbooks. Can you please help me about this matter.

Hello there. 

This isn't the kind of experience we want you to have with QuickBooks Online (QBO). I'll share the computer specifications and web browsers you can use that best work with the program so you can manage your business growth and transactions smoothly.

You can have the best QuickBooks experience when you're using the recommended (Windows 10, Intel Core i5 or OS X "Big Sur" 11.1) or minimum (Windows 10, Intel Core i3 or OS X El Capitan 10.11) operating systems, internet speeds (3 or 1.5 Mbps), and supported web browsers (Google Chrome, Mozilla Firefox, Microsoft Edge, and Safari). 

Please see this article for the complete details: System requirements for QuickBooks Online and QuickBooks Online Accountant.

In case the issue continues, even if you're already using all the requirements needed, I'd recommend performing troubleshooting steps (delete or clear cache and cookies) to rule out the possibility of having a browser issue.

Once everything is all set, you may also want to check out one of our Help pages as your reference in managing your account and business transactions in QBO: QuickBooks Learn and Support. It includes help articles, Community discussions with other users, and video tutorials, to name a few.

Let me know how it goes so I can assist you further in managing your business growth in QBO. I'll gladly help. Take care, and I wish you continued success.