A client with a Drupal web site that is growing too fast asked us to assist with performance problems they were experiencing. Pages would take too long to load.
Upon closer examination, we saw that certain pages were taking up to 6 seconds to load. Using the devel module we found the following picture:
Executed 314 queries in 3198.5 milliseconds. Page execution time was 6280.94 ms.
This means that the database was bogged down, and there is some overhead in PHP as well.