It's important you're able to use QuickBooks Online without experiencing speed issues. I'll be glad to assist you so you can enjoy using the program with peace of mind.
There hasn't been any reports about speed issues when using the program. Based on the info you've provided, I recommend clearing cache and cookies so you can to determine if it's a browser-related issue. Clearing cache and cookies is a great way to clean your browser allowing it to work more efficiently. Here's an article that shows you how to do that: How to clear cache and cookies. If this doesn't work, I suggest using a private/incognito window to see if that works instead. Try this out and let me know what happens. In case this issue persists, I encourage you to contact our support team so they can assist you further with this. Here are our contact details:
Schedule a Callback or start a Chat: click(?) in the upper right in QuickBooks Online > enter "Contact support" > choose Contact Us > provide a brief summary > select Let's Talk > choose Get a callbackor Start a Chat.