first let me tell you i am just a blogger (not SEO expert) and WordPress site owner i find google page speed insight not reliable!
even ‘google site kit’ plugin is not optimized and thus you always find difference between GSK and Gtmetrix.
so better stick to Gtmetrix score. (although i now rarely use it)
So you can speed up your site by **host google analytics code locally through ‘COAS’ plugin** or **’commonWP’ plugin to Use the Free jsDelivr CDN or if your host provider giving you their caching plugin and even by keeping minimum plugins! (if you are using WordPress)**
and you will need a fast hosting service with dedicated VPS (or with google cloud, cloudflare all depends upon your budget!)
you can Minify, HTML, CSS and JavaScript, and Optimize CSS code and delivery.
How? just google it :)-
and also you can use fast WP themes like GeneratePress and Astra.
lastly i want to say just **test your site as real human user** (just tell your friends and family to open your site and check their first reaction! Is it about slow loading or they have to wait to load for content then certainly you have to do something!)
as i found nothing is faster than loading a blank page but will it keep your google page ranking highest? (so what’s the benefit for even 0ms loading page speed with no or less visitors because even Google’s first priority is valued content not speed rankings!)
just **give more focus on valued content rather than much focusing on site speed** that your site visitors came for. (as i made my site for visitors not for google speed ranking although it matters but how much you need to prioritize yourself !)
so in my opinion any site loading in < 3s is good! (**Gtmatrix is already giving you A**)
This is my own experience as a site owner.
hope i am able to clarify some of your doubts.
u/nbloglinks