Any Ways to Boost WordPress Performance Speed?

[Foxfire]

What ways can you recommend me to boost my wordpress performance and speed?
The thing is that one of my co-workers draw my attention to FLATsite.com (https://Flatsite.com/) static wordpress site generator.
Would like to know your views on it? Have you tried it?
Any other suggestions please?

[firemanben]

There are a number of plugins for compressing images, lazy loading images and minifying javascript and css. Just google for them

[MarcS]

Image enhancement. Oversized images are the most common reason for slow WordPress blogs.
Activate the caching feature.
Consider adopting a mobile-first strategy.
It's a good idea to enable GZIP compression.
Reduce the usage of CSS, HTML, and JS files.
It's important to update your plugins.
Check to see that your database is in good working order.

[Akshay_M]

Use a Content Delivery Network
Image optimization, keep images under 100kb wherever possible, use smaller file types - - jpegs not pngs and run them though an optimizer like tinypng (Google it) before you upload to the site
Caching, caching, caching
Compression
Eliminate render blocking resources
Defer unused CSS
Avoid unnecessary plug-ins like page builder or slider plug-ins, build everything in PHP templates
Asynchronous loading of resources wherever possible, defer unnecessary elements.

[ORLOVA]

Understanding how fast your website loads is the next step towards improving site performance. Tracking site speed is advisable should you install a plugin or make some other change to your site and want to see how it affects site load times.