>The curious thing is how can you be "100% sure" in making a completely wrong statement, rather than some lower number, like "12% sure".

The reason is very simple and surprisingly straightforward (but requires some understanding of compilers): dynamically typed languages that are amenable to interpreter implementations are very hard to compile AOT. Now note I have since the beginning emphasized AOT - ahead of time - but this does not preclude JITs.

But in reality I don't really care about this aspect - it was the other guy who for whatever reason decided to flaunt that clisp can be compiled when comparing it with Mathematica.

For someone playing with Mathematica, you have an curious intellectual process. To be clear, I'd rather have you doing that than hocking loogies at cars from an overpass.