First of all, I’m no pro at this, I just figured some stuff out myself and thought I’d share it with the community.
Getting a high ‘speed’ score in google pagespeed insights is relevant for SEO purposes (you’ll have a higher chance of ranking higher in google because google favors fast websites)
The following helped me to get a higher score in Google pagespeed Insights:
Make sure all images on your site are as small as possible (while still remaining of good quality if you don’t want your site to look like crap. I use https://compressor.io/ to quickly compress my images for web use.
Clean up unused interactions (when I found this out my score went from 55 to 75 on desktop)
Set no default URL. Doing so will redirect the visitor too many times, google doesn’t like that apparently.
Clean up unused CSS styles.
Doing all of the above almost always helps me to get a desktop score of around 90.
Like I said, I’m no expert so if anyone has anything to add please do so!