The main tips I can give for a high page speed that most websites don't do are avoid large header images, make sure text is visible before custom fonts load, use minimal CSS (and/or inline the CSS for the header into the top of the HTML), don't use blocking JavaScript and especially avoid huge JavaScript triggered cookie popups (the blocking JavaScript + big delay for the Largest Contentful Paint will kill your score).
Are you sure? Have you tried using a CDN?
> An ultra small, static site can sometimes get 100 though
Here's an example site I run that gets a close to perfect score that has a fairly complex landing page:
https://developers.google.com/speed/pagespeed/insights/?url=...
(it should load close to instant once it connects in your browser: https://www.checkbot.io/)
The main tips I can give for a high page speed that most websites don't do are avoid large header images, make sure text is visible before custom fonts load, use minimal CSS (and/or inline the CSS for the header into the top of the HTML), don't use blocking JavaScript and especially avoid huge JavaScript triggered cookie popups (the blocking JavaScript + big delay for the Largest Contentful Paint will kill your score).