Why is D slower than LuaJIT?

[Ary Borenszweig]

Lua is a proven, robust language

Lua has been used in many industrial applications (e.g., Adobe's
Photoshop Lightroom), with an emphasis on embedded systems (e.g., the
Ginga middleware for digital TV in Brazil) and games (e.g., World of
Warcraft). Lua is currently the leading scripting language in games.
Lua has a solid reference manual and there are several books about it.
Several versions of Lua have been released and used in real
applications since its creation in 1993. Lua featured in HOPL III, the
Third ACM SIGPLAN History of Programming Languages Conference, in June
2007.