Major Database Performance issue on opencart 1.5.6.4 website

Hi, We have a server that is generally running fine with a couple of hundred websites. Its a WHM server with Cloudlinux 6.8. Starting today one of the opencart websites (version 1.5.6.4) started performing very bad. 45 second load times and sometimes 500 error message. There could have been a bit of a spike as they made a release today (but they do this monthly and never had this issue. site averages around 56000 visits per month). This also has affected the other opencart website on the server (same version 1.5.6.4). And no other MYSQL based website is affected. So sites like WOrdpress are not affected. Whats strange is that these 2 opencart site have been running perfect for 3 years and this just started happening today. Interesting enough, we have a test opencart site setup and it was running fine. But as soon as we pointed that to the live opencart database, it started performing slowly. SO the issue seems to be MYSQL related. And no updates have been done to this site in years. I had my server admin look into this and the results are in the text file attached. I'm looking for an opencart expert who understands DB who understands and can fix the issue. This matter is urgent.