When the login page is loading it’s still fast (1 sec) but when nextcloud is loading the files or calendar or admin setting, actually every page it’s very slow(17 sec).
Same with you, especially I am just on my local computer, the average response time also reach to 10s. The difference is I even have no heavy load on my computer.
This case is two years old. Please open a new topic and provide more information about your system. Best is to use the issue template (app in nextcloud for admin users), answer all the questions and provide the mentioned logs.
Please be aware that no-one can solves problems which are just described with “it is slow”. The better the issue description and the steps you already tried, the higher the chances to receive a solution.