1. Framework + theme.
A theme is the foundation of your WordPress website, and if the theme is not built well your website can get very slow very quickly.
2. Hosting Company.
A good host is very important and you should choose it wisely, even if it’s a bit more expensive. Things to look for: fast speeds, solid performance and support.
My favorite and what i’m using for my website is Flywheel.
3. Image Compression.
All the images on your website should be compressed and optimized.
Yes, with plugins you can do many things and there are plugins for almost everything, but you should use as less as possible.
I am using 4 plugins for my website: Elementor (builder), Advanced Custom Fields, Rank Math SEO and TinyPNG (image compression).
You can have your website tested at GTmetrix.