The system QuickBooks Online is very slow when executing any command or opening any new window.

Hello, Mk-Contracting-LLC.
 

It looks like you’ve posted this twice in our forum. I just shared an answer for you on your other post. If you haven't seen it yet, you can find it by clicking this link: https://quickbooks.intuit.com/learn-support/global/manage-your-account/quick-books-server-work-slowely/01/1608172#M10580

If you have further concerns, please feel free to reply to this thread. We're here happy to help.