100% CPU usage after updating wordpress to 5.2.2

Slowness/high CPU usage could be due to (but not limited to):
– A poor or memory intensive theme. Switch to the WordPress default theme and test loading time and see if you see a difference. If you do, may be your theme can be re-written to be more efficient.
– Poor or memory intensive plugins. One by one disable plugins and test loading time and see if you see a difference. If you do, may be that plugin can be re-written to be more efficient.
– your server is slow (e.g., “process hang”, overload, you get a lot of visitors, other problems, etc.); generally, every inexpensive host out there is slow.
– I don’t know if you use CloudFlare or not but if you do I would suggest deactivating it and seeing if it helps. Also sometimes a good purge of the cache on CloudFlare can help.
– Lots of images can cause slowness. Also images loaded without compression. – Lots of external content (facebook/ gravatar/ google adds, etc.) and redirects in general tends to slow sites down.

Tools for Site analysis:
https://tools.pingdom.com/fpt/
https://developers.google.com/speed/pagespeed/
https://gtmetrix.com/leverage-browser-caching.html

Here’s a couple of links that might give you some ideas on how to better deal with this:
* https://docs.woocommerce.com/document/troubleshooting-a-slow-site/
* https://woocommerce.com/2016/03/woocommerce-speed-first-steps/
* https://wpengine.com/blog/site-speed-make-wordpress-lightning-fast/

Use plugins to optmize/speed up sites. For example:
Autoptimize
WP Super Cache

Use Jetpack’s Photon option to speed up image delivery.

Also see thishelp guide: https://www.wpbeginner.com/beginners-guide/speed-wordpress-save-images-optimized-web/

Also review these help guides with some useful optimization tips:

Optimization

https://www.wpbeginner.com/wordpress-performance-speed/

@t-p It was brute-force attack on wp-login.php
I tried to find what part of site is under attack and what is the type of attack
after viewing the charts and monitors it was on wp-login.php and brute-force

1 – We changed the default login url ( Recommended to all wordpress sites )
It can be done by changing it in wp-login.php file in your wordpress directory need to write plugin using hooks
Or the simplest way is to using ready plugins..

2 – Forbidden all of access to wp-login.php by editing your htaccess ( you can use this link )

Nicely done . I dont recommended to use web application firewalls plugins cause it can reduce the performance of your site .

Best Regards

Glad it’s sorted ??