From the code I've read, Lua is easy to read and I hear it's really great to write in, and it's performance seems to be quite high.
Comparatively in the startup and SaSS world I almost never hear about it. Is there any profound reason why? Is it because it doesn't quite fit into web technology stacks as well? Is Lua simply better when we're talking about high-performing desktop apps, where the painful alternative is to simply do it all in C/C++/Rust?