The Luau FAQ[1] when they first announced the project mentions that Mike Pall post. I assume they do the computed goto trick for fast interpreter dispatch (or just have some inline assembly now).
They explain it in some subsequent page. Also computed goto is not really performant enough for fast scripting languages, it's essentially a switch (indirect func table) without range check.
The performant variant is to squeeze it to have room for other code, keep important registers asis, and jit the bytecode array into sequences of static calls.
They next best variant is to call the next op statically. Indirect func tables are hard to predict by the CPU.
They explicitly removed tailcall for better user experience, as it messes up debugging and stack traces. Maybe it could be added back in perf mode.
1: https://gist.github.com/zeux/bb646a63c02ff2828117092036d2d17...