CPU

For sites that have lots of slow queries, disk access is often the bottleneck. For these slow queries, MySQL writes temporary tables to disk, populates them with intermediate results, then query them again for the final result.

We all know that the disk is the slowest part in a computer, because it is limited by being mechanical, rather than electronic. One way of mitigating this is to tell MySQL to use memory rather than disk for temporary tables.

While doing a Drupal Performance Assessment for a clients Drupal 6.x site recently, we found an odd problem.

Among other things, page generation times was high, and this was due to the function skinr.module::skinr_preprocess() was being called 190 times for each page load.