Those Page Speed results can be misleading as they usually complain about exactly the things you cannot change (as they are part of the IPS framework) and they don’t tell you about the things you can change.
It’s much better to focus on the things in your control.
The server and all its components play a huge role. That’s the admin’s responsibility for self-hosted installation.
Caching of resources and maybe even full pages. Plenty of optimization potential here!
Third-party interference. Loading external ads, analytics, webfonts … that slows down the site significantly.
And then of course: what’s on the page to begin with? I often see community sites completely overloaded with blocks, trying to announce everything the site has to offer on the homepage with sliders and sometimes hundreds of avatar images to be loaded, plus external ads everywhere … Of course such a page will be slow to load. IPS can’t fix that with framework updates.