Manual:$wgEnableSidebarCache/ja

詳細
true の場合、サイドバーのナビゲーション リンクをキャッシュします.

If on, the sidebar navigation links are cached for users with the current language set. This can save a touch of load on a busy site by shaving off extra message lookups.

However it is also fragile: changing the site configuration, or having a variable, can produce broken links that don't update as expected.