Very slow Magento 2.3.5.p-1 - What can I do?

I finally finished my shop and it will be ready to open for public soon :D.
What I noticed is, that the shop loads very slow.

I had it run through GT Metrix and it is answering very slow.

PageSpeed Score

(44%)

YSlow Score

(70%)

Fully Loaded Time

19.5s

Total Page Size

4.76MB

Requests

393

The fully loading time varies between 19.5 and 69s. So I was wondering what I can do to get the shop faster?

Of course varnish is enabled and I also use Cloudways CDN.
In Magento CSS, HTML and JS bundeling, minify and loading at bottom is enabled.
It is a digital ocean server, 4GB, 2 cores, 80GB disk.

Happy for any tips :smiley:

HI,

Improve the executation time such as change PHP version, increase disk space,…
If possible, please upgrade Magento to the newest version (2.4).

use varnish