What is the best way to build super fast html responsive site

One of my sites is still not responsive, build with tables…
what is the best way to make it responsive for mobile phones?

I want non cluttered super fast load etc…
I checked skeleton foundation and I like it…anything better

I think bootstrap uses JS and that slows down the website speed?

Skeleton looks like a fine framework, but it hasn’t been maintained in 4 years, so it’s unlikely to be using modern technologies like flexbox. I suggest you first try Bootstrap or Zurb Foundation and see if they’re actually slow. Chrome provides a number of hooks and tools for measuring rendering performance, such as the “timeline” tool. Don’t guess about speed without actually measuring it.

what about kraken? It supports flexbox…

No that’s not true.

Bootstrap is used by 90% sites as on today to make a responsive websites.

media-query-css

Do you know you can also make responsive websites using CSS Media Queries only.