Manual:$wgMainCacheType

Details
Object cache setting. Replaces $wgUseMemCached.

Here are the available CACHE constants, as defined in Defines.php


 * CACHE_ANYTHING - Use anything, as long as it works
 * CACHE_NONE - Do not cache
 * CACHE_DB - Store objects in the database table objectcache table.
 * CACHE_MEMCACHED - memcached, must specify servers in $wgMemCachedServers
 * CACHE_ACCEL - APC --> XCache (--> WinCache, if on Windows), trying each in this order, using whichever is available


 * CACHE_DBA - Use PHP's DBA extension to store in a DBM-style database in $wgTmpDirectory with $wgDBAhandler


 * Roan Kattouw has stated that CACHE_MEMCACHED directive will provide the most significant performance improvements in the case where you have memcached and an opcode cache installed. APC still caches (others may as well) though it is unclear if it is used in the final transaction with the client.
 * This is just one of MediaWiki's caching settings. For best performance you may need to consider other caching settings, such as $wgParserCacheType. See also Squid or Varnish which can help a lot.