DB queries in main.ejs and session storing or caching to reduce query volume?

[Apple]

You're welcome. Also read this:

Retrieve logged user data

While setting a session cookie with the information you need (e.g.: name, surname, permissions, etc.) is the most efficient approach, it’s not the most secure by default. I once had the opportunity to view a user being banned, but because sessions weren’t purged from the server, he continued to have administrative rights. So, I prefer to perform a database query every time instead of storing data in sessions, even if that comes with a trade-off in performance.

Also, if you use internal links (SPA-style), I don't think the server connect is reloaded on every page change