Extremely slow response times

My multi-site has slowed extremely of late . I have contacted my Webhost and I got this response:

"the site seems to be using quite a bit of resource per request at the moment which should be looked into, It's only able to run 2 simultaneous loads within the CPU allowance given. this is pretty excessive and needs to be looked into what's causing the load.

Although it shares the resources then two processes using all the CPU are both originating from /home/XXXXX/public_html/ which is the main sites location on that cPanel.

Both those processes are running again currently causing the slow load times.

777055 lsphp:disappointed:home/XXXXX/public_html/index.php 52% 67
777065 lsphp:disappointed:home/XXXXXpublic_html/index.php 52% 67

My question is, can someone help me find exactly which plugin/theme is causing the trouble? There used to be a plugin called p3 profiler, but they've stopped updating that. What should I be looking for?