1. Remove all unwanted plugins.
Sometimes users keep old plugins by simply deactivating them which can cause issues with CPU/Virtual Memory usage or utilization.
2. Update the plugin to the latest version available.
Plugins involve updates needed to fix their bugs or any issues that may cause further complications to the plugin itself which may cause other related issues mostly on CPU/Virtual Memory usage.
3. Optimize the table database routine.
To keep things running smoothly, you need to log into PhpMyAdmin regularly and optimize the database tables. Data tables that are not optimized can overload the server. In addition, it also uses more CPU to read data tables that are not optimized. In addition to data table optimization, you can also delete spam/unapproved data.
4. Theme usage and compatibility.
This is the most common reason or cause for the CPU/Virtual Memory limit issue. Before proceeding to install a theme, it is best to check its compatibility and requirements as usually some fancy themes require more resources to operate normally.
5. WordPress updates and caching.
Are you still behind with older versions of WordPress? Well, if so then it is high time you upgrade to the advanced and latest version. Most of us ignore the idea of upgrading wordpress just because it's working perfectly. Updates help because newer versions are better in terms of security and optimization.
You can also install a wordpress caching program. Caching archives every web page on your site. This lowers the server load as it does not require sending many queries to the database to generate many pages.
6. Reduce the use of widgets.
In particular WordPress run by users may contain some unnecessary widgets which usually cause complications where more usage on CPU/Virtual Memory is required to operate.
7. Drop the PHP or Database call.
PHP scripts and database calls also consume a lot of CPU resources. Caching your site helps but certain database/PHP calls are unavoidable. Hence, you should read the plugin documentation carefully and disable unnecessary options.
8. Lower the load on the index.php file.
During peak hours, your homepage may create a load on your server during peak hours. To lower this load, make sure to keep your homepage simple. Try to lower the number of posts on your homepage and remove unwanted files, links, and high-resolution images. It would be even better if you choose a CDN service like Cloudfront
9. Disable WP-Cron.
Disable WP-Cron or change it to a scheduled task to run every hour. This will greatly reduce your CPU usage. WP-Cron manages all your scheduled events so that it continues to be active on many sites when not needed.
10 Avoid plugins that use excessive CPU load.
These are often backup and security plugins. These functions are best offered by quality host providers that have integrated solutions.