From the absolutely non telling data point of 1 I can say that caching solutions and their over aggressive use break down at least as frequent as the databases.

From the absolutely non telling data point of 1 I can say that caching solutions and their over aggressive use break down at least as frequent as the databases. First thing - break with the or die(mysql_error()) pattern Second see if everything is properly and workingly indexed. Third - take a look if you are doing something that is not needed. There are a lot of parasitic queries left in any big project. Fourth - a very successful approach that I have used is to create the majority of slow content in static files that are generated from a cron. Disk based io is easier to scale and you leave to the filesystem to do the caching. Rule of thumb for me - if 3 minute delay is not fatal and it will be common for all users - it goes in the static.