Moodle offers a wide range of system-related performance settings that are set at various places in the Site administration menu.
Caching stores frequently accessed data in a temporary storage, and expedites its access using the cached copy as opposed to re-fetched (from disk) or re-computed (in memory) data. It has proven to be one of the most efficient performance optimization techniques and Moodle is no exception.
Moodle has some basic built-in caching and manages memory allocation and compression automatically. Additionally, you might consider installing a caching system such as eAccelerator, APC or memcached. Please refer to the respective documentation on how to set these up.
The principal trade-off in caching is between refreshing the cache too often (small values), which slows down the server and refreshing it not often enough (larger values), which potentially means values are not updated on time. There are a number of caching-related settings:
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