Manual:$wgUseGzip/ja

詳細
When using the file cache, we can store the cached HTML gzipped to save disk space. Pages will then also be served compressed to clients that support it. In older versions of MediaWiki it also controlled if normal (non file-cached) pages were gzipped.

これは、一部の利用者が LocalSettings.php で有効にしていると思われる ob_gzhandler と互換性がありません. ( を参照してください. ) これを有効にする場合は、先に前述の設定を除去してください. It is also incompatible with automated gzipping done on the server side (e.g. mod_deflate) and zlib.output_compression

PHP の zlib サポートを有効にする必要があります.

Between 1.2.0 and 1.3.0 (inclusive) the default value was true if the function 'gzencode' is defined, otherwise false. For prior and later versions it defaults to false.

注記
You can test your website compression here: http://www.whatsmyip.org/http_compression