You should establish performance goals to ensure you spend effort wisely.
Caching to improve performance
There are several techniques to increase the PHP memory limit. Use the right one for your system configuration.
A CDN offloads much of your site delivery to a network of dedicated edge caches.
Drupal offers a variety of tools and features to reduce bandwidth requirements, including:
note: increasing PHP upload size is different from increasing PHP memory limit. You can learn to increase memory limit here.
Details of how to optimize MySQL for use with Drupal.
Sometimes malicious HTTP GET requests can take down your site, by bootstrapping Drupal so frequently that you can exceed a MySQL max_user
The performance of your Drupal site is dependent on three main factors: the goals of your site, the resource demands of your site traffic,