As the title asks, what apps are you running?

I don't even use Nextcloud for files 😆 (except for syncing things)

I use PhoneTrack as an alternative to Google Find my Phone (including Android app).

I use Cookbook to track all my recipes, including Android app(s).

I use Tasks synced with the Tasks.org Android app.

I use Bookmarks for keeping track of stuff I'll never look at again.

I'm using Contacts to sync contact from phone as a backup, so I don't have to use Google.

Those are the main ones. I'm also using the Home Assistant integration so I can see some things I actually care about (not the weather, as the other commenter mentioned). And I use the Custom Menu because I like it more.

Also do you have your data on your host machine or on your main storage/NAS?

My host machine just has a big SSD.

Last question, is it just my set-up or is NextCloud slow for everyone?

Typically this is a setup thing. I always read stories about people who did X and were surprised by how snappy Nextcloud felt afterwards. Sorry, I can't remember what they did! Something about postgres instead of mysql databases or stuff with redis or things like that.