It's a custom fork of plain Lua, not LuaJIT, so indeed there's no LuaJIT support. They first open sourced it this November and supposedly they're planning to implement their own JIT. There's no timeframe or estimate for that though, just mentions of plans to here and there.
Sounds good. I won't cycle back to finish Lanarts for a while so I look forward to a JIT in this space. LuaJIT was a marvel but it probably needed a few more years of Mike Pall's time to smooth out difficult to anticipate optimization