Quick checks
If a page is slow, reload it, then try another page such as the anime list. A reload usually sorts out a slow connection.
Another device
Opening KissAnime on a phone with mobile data shows quickly whether the issue is the home network or the site.
Your list is safe
My List lives in your browser, so it stays in place through any reload. Export it from the My List page for a backup.
Watching
Anime plays on the official services, so anything you have started keeps playing in the service's own app.