Manual:$wgEnableParserCache

Parser Cache: $wgEnableParserCache
Keep parsed pages in a cache to speed up page output.
Introduced in version:1.2.0
Deprecated in version:1.26.0 (Gerrit change 212199; git #8194b201)
Removed in version:1.33.0 (Gerrit change 486713; git #d39cc0e8)
Allowed values:(boolean)
Default value:true (1.4-1.32)
false (1.2-1.3)

Details

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Keep parsed pages in the cache specified by $wgParserCacheType to speed up output of the same page viewed by another user with the same options. This can provide a significant speedup for medium to large pages, so you probably want to keep it on.

Requires that php was compiled with --with-zlib.