With a dramatic increase in customers turning to Joomla, WordPress, Drupal, etc. we've seen a huge impact on the customer MySQL servers. "mysql55" and "mysql41" in particular were getting overloaded. So in the middle of the night we performed a 5 minute hardware upgrade. Specifically, we doubled the number of CPUs, and we also doubled the amount of RAM. For several of the larger/busier sites we host the improvement was very noticeable.