In his latest blog entry, Brian Moon takes a look at using big arrays in PHP - how efficient it is and what can be done to ease things a bit.
So, at dealnews, we have a category tree. To make life easy, we dump it to an array in a file that we can include on any page. It has 420 entries. So, I was curious how efficient this was. I noticed that some code that was using this array was jumping in memory usage as soon as I ran the script.
His tests showed that the memory jump from before and after the array was significant (5 MB for his test). He tested different methods of storage for the array including a var_export and serializing the data (the lowest memory option).