How to optimize Drupal for better performance?

You've got to maintain your Drupal site properly, to keep it fast.

 
Here are some tips on how to optimize your Drupal site:

•  Enable caching for your Drupal.
•  Optimize your Drupal database.
•  Log in to your Drupal admin area and go to Site Configuration > Performance. Besides enabling cache, you should also enable Page compression, Optimize CSS files and Optimize JavaScript files.
•  If your Drupal is hosted on a dedicated solution, you can modify the global MySQL settings for better performance.
•  Check your website using this online tool. It will give you valuable information on what modifications can be made in order to improve its performance.
•  Disable/remove all modules/blocks you are not using.

(As read in: kb.siteground.com site)