My Drupal site is running really slow

You have to determine where it is slow. It is either on the server or in your browser, or both (it could be over the wire, too, but this is hard to measure).

First: install the Devel module and turn on the query timer. Take note of the number of slow queries and report them here. Also take note of the total page generation times. This will tell you whether your server is the slowdown.

Second: Get Firefox and get the Life-of-Request Info extension. This will show how long it takes to load the page into the browser, how long it takes to render it, and what other requests are involved (getting images and css files).

You should also try to get a feeling whether the pages are loading similarly fast or slow in various browsers (especially check IE).

- Robert Douglass

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My Drupal book: Building Online Communities with Drupal, phpBB and WordPress

Make sure you are using PHP caching - this is separate from Drupal caching and makes a very large difference, especially on heavily-loaded sites.

http://pecl.php.net/package/APC

As the other poster said, the next thing to do is work out where the slowdown is. Could be the database- are you using PostgreSQL or MySQL?

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