Author here! That's totally fair. I did learn this is a common technique in the embedded world and I had a whole section in the original draft about how it's not a super well-known technique in the typical "backend web server" world, but I wanted to keep the length of the post down so I cut that out. I think there's a lot we can learn from embedded code, especially around performance.

Back in 2005 Virgil I, which target MCUs like AVR, had static initialization and would generate a C program with all of the heap statically allocated, which was then compiled into the binary. C programmers for AVR are used to just declaring globals, but Virgil allowed arbitrary code to run which just initialized a heap.

Virgil II and III inherited this. It's a standard part of a Virgil program that its components and top-level initializers run at compile time, and the resulting heap is then optimized and serialized into the binary. It doesn't require passing allocators around, it's just part of how the language works.