Message from CrucialWebHost - Resource Abuse Violation - Immediate Attention Required

Hey Drupal Ninjas,

I received the following message from CrucialWebHost regarding CPU usage:

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Hello,

Your account has been flagged for violating our Resource Abuse Policy. In order to maintain a high quality of service we have established a set of resource allowances that all clients must adhere to.

Your account has violated our CPU usage restriction for 5 consecutive days and is in danger of being suspended. Your immediate attention is mandatory to avoid suspension.

http://www.crucialwebhost.com/company/legal/rap/

- CPU usage may not exceed 20% on any shared hosting account.
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11-02-2009 - 23.73% CPU Usage
11-01-2009 - 38.43% CPU Usage
10-31-2009 - 30.86% CPU Usage
10-30-2009 - 35.08% CPU Usage
10-29-2009 - 22.04% CPU Usage
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It is necessary for you to immediately reduce the CPU Usage your account is consuming or upgrade to a higher plan that allows for greater CPU resources such as a Semi-Dedicated container or Dedicated Container plan.

Your account will be reviewed in 24 hours and if CPU Usage continues to be above acceptable limits we will be forced to suspend your account to protect the quality of service for other shared hosting clients.

Please respond to this ticket with your acknowledgement and any questions that you may have.
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They then followed up with this ticket:

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After further reviewing your site it appears that your resource usage is related to a very heavy MySQL use as evidenced by your error log.

We recommend that you not use MySQLi as this is slower than standard MySQL and possibly trying to disable caching which is hitting the MySQL database so hard.

I do not know how to disable caching or switch from MySQLi to MySQL, you will need to consult the Drupal forums or documentation. However, I did notice that your MySQL database had about 40MB of overhead. You should frequently optimize this database, which you can do from cPanel in the MySQL Database section, there's a spot for optimizing/reparing a database.

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While we did have a slight spike in traffic, it wasn't anything too crazy. Can anyone provide some guidance how to switch from MySQLi to MySQL. Frankly, we didn't do anything fancy on the install, just did the typical install. Any ideas?