How can I increase the speed of my online store?

@oreoorbitz Thank you for the recommendation i did according to your advice i just need an extra advice

-block rendering (done)

-responsive hero (done

-changed instagram plugin (done)

-lazyloaded 7.png and optimized it (done)

-add width and height for what ? ( didnt understand)

now the main part into removing unused css and javascript lets start by removing the unused css
which way do you prefer ?
split my css to sections ? and make it loading accordingly to what page its on ? i can purifiy the css using some 3rd party website and make few splits of the css if you think it works ?