Performance form allows to setup some improvements in speed.
Cache prefix - cache prefix in system, required if you use shared caching system with other websites.
Cache lifetime - cache TTL (time to live), maximum lifetime of cached data.
Cache adapter - you can select adapter for the cache: file, memcached, apc, mongo. Default is file and others require additional PHP extensions.
Clear cache - select to clear current cache.
If “File” adapter is selected:
Files location - path to a folder where cached data will be stored.
If “Memcached” is selected:
Memcached host - host address of the server.
Memcached port - server port.
Create a persistent connection to memcached - will create per-request persistent connection.
If “APC” adapter has no additional settings.
If “Mongo” adapter is selected:
A MongoDB connection string - mongo connection string (read about mongo).
Mongo database name - database name.
Mongo collection in the database - mongo collection.