Hello,
Indeed, the page loads all the analyses and associated measures for your project, and that’s the main variable influencing the loading time.
This is exacerbated by this bug that causes analyses to not be purged as much. It has been fixed for the upcoming 10.4 version.
I think you should be able to speed up the loading by specifying start and end dates to limit the number of analyses to fetch.
Let me know if you need additional help.