Creation and user editing on Wordpress is really slow

Depending on the load of the droplet and if you have the database on the same system could be where your issue comes from. You may want to break up you system into several smaller droplets versus having one large system as MySQL/MariaDB don’t like to share the same system as your web server or other apps typically since they have use a lot of resources. You may also want to look into optimizing your MySQL/MariaDB setting using something like MySQL Tuner. Also, read up on some documentation for speeding up WordPress (not caching documentation), your web server, and your database. Just search “Optimize <XYZ>” on the DigitalOcean tutorials and there should be an article.