Magento 2 speed up and optimise

hello we currently have a website buywiseappliances.co.uk its currently sat over 2 dedicated servers 1 for web files and the other for database, we have had alot of work done on the site to get it to function how we want it but feel ther is more room for improvement with regards to the page loading as its currently loading in about 8 - 9 seconds

We would liek someone with a good proven track record who can assist at fixing any jquery errors that may be contributing to the site running slower as well as working towards a W3C compliance