Improving Drupal Speed
Drupal is a fantastically powerful content management system. But that power comes at one very significant cost, speed. A Drupal powered site may suffer from slow page loads.
This very blog is powered by Drupal, and I admit that at times its speed is on the slow side. I have recently found a few ways to improve the speed. These are:
Drupal has built in caching capabilities. This caches the output of pages and therefore reduces the number of database queries when anonymous visitors (visitors who are not members of the site and therefore not "signed in") access the website.
To enable caching, go to: Administer » Site configuration. Turn caching mode to "Normal". You can try advanced caching, but this does come with side effects, so is not recommended unless you really know what you are doing.
When setting the minimum cache lifetime, the longer the better in terms of speed. The cost is that visitors will not see new content for the set amount of time. As a guide, I have set this blogs minimum cache lifetime to 3 hours.
Aggregate and compress CSS files
Aggregating and compressing CSS files saves on valuable bandwidth and can offer a significant speed boast.
To enable CSS file aggregation and compression, go to: Administer » Site configuration (as with caching). Turn Aggregate and compress CSS files to enabled.
Remove unwanted modules
There is no point in having modules that you do not use enabled. Modules lead to extra database queries, so turn off any modules that you do not use.
Enabling caching and CSS file compression/aggregation has improved page load times on this site but approximately 50%. I admit, there is still room to improve the speed further. I will report back when I find other ways to improve the speed of Drupal.