I think that we should possibly install luasandbox which goes with Extension:Scribunto. It was created and is used by wmf.

“LuaSandbox is an extension for PHP 5, PHP 7, and HHVM to allow running Lua 5.1 code from within PHP, which will generally be faster than shelling out to a Lua binary and using inter-process communication.” -https://m.mediawiki.org/wiki/LuaSandbox