improve page load speed - potential site reinstall needed for theactivehealthclinic.com

I wanted my site to run faster - i employed an "expert" from India on uplift - things went badly. He would never tell me what he actually had done. I could see he basically played around with variations of cache plugins i had already installed. They ended up refunding me. I now have a site that doesnt work with menus and i cant log into the back end of the site. I took a back up of the whole site - all files, and the database before they started work 7 days ago. I think its time I just rolled back and optimised things myself with plugins like before - it was satisfactory and at least was working adequately. I am nervous about doing the whole wordpress re install thing. The "developer" has left suspect files on like [login to view URL] and .quarantine folder (this may just be him being safe in his opinion - screening things). He's increased the website size by about 1.2 GB! i expect by leaving back up zips in folders that werent excluded from backups and hes been also backing up cache from temp image files that should have been deleted when he was trying different plugins. I expect it is salvageable without reinstall and i will start working on that now. But it maybe quicker to delete everything through cpanel and then start again. The only problem is I suspect my previous backup was not a great set up as the page load speed was very slow anyway. But it is better than what we have going on right now. Would like to know the quote for reinstalling from back up - once this is done then we can have a good chat about what can be done and agree on a price for the further work? Just an idea on the best way forwards. site is the [login to view URL] I have the full back up, including database before the work was started and a day into it also.