Rebuild and optimise a homepage

General information for the website: -
Kind of development: Customization of existing website
Num. of web pages/modules: 1
Description of every page/module: The home page
The website is build with the premium theme the7 with visual composer

Today i have a Website which is not fonctionnal

The homepage is still 8MB with 2 CSS files that make 5MB !! At this level there is delirium.
This page when it is loaded 25% of the processor of my workstation
full of machines that does not even display it (iphone, ipad, descktop, ...)

The problem is only on home page loading but all the pages should be optimised
On ipad and Iphone : impossible to load the home page : the phone and the tablet are frozen and we can't make any scrool to the pages

Firstly
I need someone who can recontruct the home page properly from stratch on the same design as existing but more light and responsive fully integrated

the home contain :
- a slider video
- A white bloc with text and logo
- a dark blue tabs system with pictos, text and dual buttons in each tabs
- a parralax title separator with text and content
- a dark violet tabs system with pictos, text dual buttons in each tabs
- a parralax title separator with text and content
- a dark green bloc with 2 sliders of logos
- a parralax title separator with text and content
- a new bloc with 3 news (uploaded direcly when a news is created)
- a parralax title separator with text and content
- a Logo slider with Square logos
- a parralax title separator with text and content
- a contact form

Secondly,
Optimise and make a stylesheet more light and more efficient.
Optimise the loading duration : we need optimise the loading time and solve all issues.

then. optimise the GTmetrix score at B (pagespeed) and B (Yslow)

The exemple of the page : www.expertisme.com/home-awais
Description of requirements/features: -
Specific technologies required: css, visual composer, wordpress, gtmetrix optimisation,
Extra notes: