Long TTFB even without any plugins

Hello. I run a e-commerce website on a $30 VPS hosting, free Cloudflare CDN and Flatsome theme.

Please give me an idea what can be slowing down my website. Even when all the plugins are disabled.

TTFB is still around 500-700, that’s huge.

Shortly:

all images are optimized and lazy loaded,

video embeds,

cache and other basic

advanced optimizations like CSS and script removal are applied too