What is the best way to improve my clients' site page speed?

this is the site - http://www.amorpure.com/

it never used to be this slow but for some reason, it is being slow and jumpy and looks very unprofessional. I did not create this website, some guy did in India, but have helped to improve content when needed. However, I just did a pagespeed insight and it came back terrible results.
so my question is, what is the best way to improve the sites’ speed? should I tell my client I need to re-do this website? I’m mean it is messy when you inspect and like I keep getting console errors so I really don’t know how to begin? another example is when I watch the site video on a mobile device, the video has moved up? I really don’t know how this has happened??

If you open the developer tools in chrome you can run an audit in performance and it will tell you what is slowing down your page, for starters you could:

  • optimize the quality of the image, that should make it between 5 and 9 seconds faster to load the page
  • remove duplicates being downloaded, for example jquery and jquery.min are both being imported on the page, that shoud improve another 2 to 5 seconds
  • lazy load the images always helps to improve loading speeds
  • load only the parts of bootstrap you need per page could also improve a couple seconds
  • lower the amount of javascript errors that way the page won’t block as often and you can improve the loading up to 10 seconds, i put this last since it’s probably what will take longer

This is some points that could get you started in improving the website without having the need to rewrite it completely, you might get it from the current 40 seconds to probably 10 or 5 seconds, which is still not brilliant but would be a whopping 300% improvement regardless