In my case helped alot to uninstall all EE modules, and downgrade to CE.
That was the biggest improovements.
Then second good thing was to create indexes in DB.
Still I am facing alot issues and functions I was expecting to have it OK out of the box, but not (GZIP not working, too much uncompressed JS and CSS, syntax of html served is not ideal, some stuff aare blocking page rendering., etc.....there is bunch of improovements on pagespeed.web.dev ...need to fix one by one, it is not blast fast, but working just fine.....could be better. Let me know if you will find any improovements.