Performance issues can be complex and difficult to track, in many cases it is hard determine the exact problem. The more detailed information you provide in advance, the better we can try to recreate the problem on our local environment and identify the underlying issues.
Please try to answer the following questions:
Where do the issues occur?
Can you spot pages or actions that are slower than others? For example the dashboard or a certain Confluence page. Often macros or other third-party-content affects performance.
So it is very important to know, what the content looks like exactly. A screenshot of the page or action is always helpful for a better understanding.
What is slow exactly?
A slow loading page can have many indicators. For example some customers notice a white page for a long time before any content is shown. Long loading content, indicated by a spinner or a loading wheel. Sometimes the whole page seems to stuck while rendering
What third-party-apps are installed on the system?
Third-party-content may heavily affect the system performance or the loading time for certain pages (e.g. by macros). Therefore it is always interesting to know which apps are used.
If you notice performance issues after installing / updating a certain app, you might test to deactivate it and see if the system is still slow.
Do the problems occur in certain browsers only?
Do the problems occur during certain times of the day only?
For example ...
... in the morning after a "quiet" night?
... at times when many users are working simultaneously on the instance?