Virtual Memory Size Exceed Limit

Hello.

I need the expertise of your party. Recently my website problems. It has led to a remote server is interrupted. It also has resulted in hundreds of websites that are using the same server was interrupted. They have to report to me. Here is his report:
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Dear Najib,

Your website powergold.com.my is consuming alot of memory RAM, more then 300MB continuously.
A share hosting website only allows 100MB of RAM per website.

Below is one example which shows your website consuming 368MB of RAM at your website first page index.php.
- Time: Mon Dec 2 10:54:38 2013 +0800
- Account: powergol
- Resource: Virtual Memory Size
- Exceeded: 368 > 300 (MB)
- Command Line: /usr/bin/php /home/powergol/public_html/index.php

Do you know the reason or is able to fix it by disable unnecessary plugins or resource usage.
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Dear Customer,

You can download all the web content and database to your local computer conduct testing with it. You can remove the entire wp-contents > plugins folder to temporary disable all plugins , and enable it back one by one to check.

Below is the latest report from the server which your account still consuming more resources than allocated , by a schedule task.

Time: Tue Dec 3 09:27:03 2013 +0800
Account: powergol
Resource: Virtual Memory Size
Exceeded: 368 > 300 (MB)
Executable: /usr/bin/php
Command Line: /usr/bin/php /home/powergol/public_html/wp-cron.php
PID: 31550 (Parent PID:30494)
Killed: No

Please do not hesitate to contact us if we can be of further assistance. Thank you!
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Dear Najib,

We are suggesting it may come from your plugin.
You may need to disable the plugins that you do not need, upgrade your website script to latest version or add CAPTCHA image to comment pages.

Below alert indicates clearly that command that is trigger is from "public_html/wp-cron.php".
So you may check it out.

- Time: Tue Dec 3 17:24:34 2013 +0800
- Account: powergol
- Resource: Virtual Memory Size
- Exceeded: 367 > 300 (MB)
- Executable: /usr/bin/php
- Command Line: /usr/bin/php /home/powergol/public_html/wp-cron.php
- PID: 6617 (Parent PID:6522)

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Dear Sir,

The issue persist on last check, below is the log:

Time: Wed Dec 4 01:00:14 2013 +0800
Account: powergol
Resource: Virtual Memory Size
Exceeded: 364 > 300 (MB)
Executable: /usr/bin/php
Command Line: /usr/bin/php /home/powergol/public_html/wp-cron.php
PID: 21523 (Parent PID:21358)

Please do not hesitate to contact us if we can be of further assistance. Thank you!
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From the reports I have indicated, they claim it is caused by the plugin. I'm stuck, because they have a lot of plugins deactivated. But still does not solve the problem. Therefore, I ask for help from among you who could possibly help me. FYI they have suspended my account twice!