1. Inspect every installed 3rd-party extension
Magento 2 core is written by programming experts. There is not much room for improvement in the core code. That is normally not the case for extensions you can buy, or download for free. Some of them could really slow the site down.
You should perform a 3rd-party extensions audit. Turn every module on and off, clear caches, and see if it changes the site’s speed. Test all important page types, front page, category pages, product pages and checkout. If you turn off an extension and the site becomes faster – you have found an abuser. Contact this plugin’s vendor and let them know about the performance problem. Ask for a refund, write a review, and find an alternative if they don’t respond.
To turn off the extension you will need SSH access. Most hosting companies will allow you to access the server via SSH and will provide you with necessary credentials.
Once you are logged in issue this command to disable VendorName_PluginName plugin:
php bin/magento module:disable VendorName_PluginName
To turn it back on run:
php bin/magento module:enable VendorName_PluginName
To see what modules were disabled or enabled run this command:
php bin/magento module:status
The other way to disable an extension would be to simply delete it from app/code folder. You would need to follow it with this command:
php bin/magento setup:upgrade
If you want it back – just copy it to app/code and run the same command:
php bin/magento setup:upgrade
It is always good practice to delete unused extensions from the file system, they will just be an unnecessary security risk.
2. Choose the fastest hosting you can afford
3. Turn Caching On
4. Turn Production Mode On
5. Never Use JS Bundling
6. Enable CSS/JS Minification
7. Use Built-in Cache, Skip Varnish