Urgent: My website consumes 100% CPU and I can not find out what is going wrong

Hello, forum!

My case is rather urgent due to pressure from my hosting company.

I have recently tested my website loading time with pingdom and to my surprise I found out that something goes terribly wrong. Most of times waiting time consumes 1/2 – 2/3 of total page load. In the sample URL (https://tools.pingdom.com/fpt/#!/JyyRTtw9l/https://altclass.com) you can see by yourself that 3.2s out of the 4.56s required for loading my website was consumed as waiting time.

I decided to contact my hosting company and inform them of my issue. They checked their server and claimed that problem occurs only with my account since my website consumes 100% of available CPU. They also warned me that if this persists then my account will be suspended.

In an attempt to help me solve the problem they suggested the following steps:

a. Reduce the number of posts on the front page of my blog
—– As you can see that is not a problem for my front page as it is kept as simple as possible without any images attached —–

b. Install anti-spam plugins in order to prevent spam-bot from creating load on the server.
—– I already run the free version of Anti-Splog —–

c. Optimize my WordPress database.
—– I have done so through my cPanle tool phpMyAdmin —–

d. Install a caching plugin such as WP-Cache or WP Super Cache.
—– I am not sure, but after having checked the W3 Total Cache plugin, I found out that no such plugin should be used until site development is completed – maybe referring only to css? My site is still under construction. —–

e. Decrease the number of external and internal links on my pages and leave only the most important ones.
—– You can check it out, but I believe that links on my pages are not that many. It is hard to believe that is the base of my problem. —–

Lastly, they have insisted that I have to address this problem to WordPress so that experts check my website and find out what is going wrong in my case.

I am using WP-Multisite, BuddyPress, s2Member and bbPress to ensure compatibility. I have never placed a hand on parent files, other than wp-config.php to enable subdomains and debug-mode. Instead I have created a child theme which I have testes with W3 XHTML validator (still 4 errors that I do not know how to fix) and Theme-Check plugin (everything looks fine).

Can someone please help me with this case? I can not afford getting my hosting account suspended and I am not sure if my hosting company is speaking truth or they are taking advantage of my inexperience.

My website is

https://altclass.com

Thank you in advance for any support. I have faith on this forum, but I shall also let BuddyPress know of my issue. I am not sure how I should proceed…