Lua was chosen over JavaScript for its ease of embedding. It's easy to limit how much memory the Lua interpreter uses to prevent users from DoSing Wikimedia ser

Lua was chosen over JavaScript for its ease of embedding. It's easy to limit how much memory the Lua interpreter uses to prevent users from DoSing Wikimedia servers with templates. V8 and SpiderMonkey do not make this easy. More details here: https://www.mediawiki.org/wiki/User:Sumanah/Lua_vs_Javascript https://www.mediawiki.org/wiki/User:Sumanah/Lua_vs_Javascrip... Wikipedia pages are massively cached: rendered pages are cached in Squid, and I believe parsed page contents are stored in memcached. Templates are only re-rendered when pages are edited, if all goes well.