Nowhere in this article does it really state that they're less productive in Lua, though. In fact, the main engineer on it is well versed in it. Your 5% may actually be negative in this case.
From where do you get this impression that Python is the only high productivity language in the world? There are plenty of languages that can compete with Python in terms of productivity and a lot of them offer better abstractions for it. Lua is known for being one of the best escape hatches for scripting.
If you're more productive in Lua than in Python then I support using Lua 100%. It's switching languages to gain a measly 200MB of disk space that I'm objecting to. For 99% of projects 200MB is just an irrelevant consideration compared to how much difference language productivity makes.
For general cases, I agree that 200 MBs isn't enough to consider very important nowadays, but I still don't get how we're automatically talking about language productivity being a trade-off. Is the assumption that Python is a more productive language regardless of what it stands against?
btilly was talking about the disk space as if it were important.
My opinion is that Python is more productive than Lua, but if you disagree by all means use Lua. But if you're talking about saving 200mb of disk space as though it makes the difference, then I think you're using the wrong criteria for choosing your language.
From where do you get this impression that Python is the only high productivity language in the world? There are plenty of languages that can compete with Python in terms of productivity and a lot of them offer better abstractions for it. Lua is known for being one of the best escape hatches for scripting.