Indeed it doesn't mention the instruction set. The closest would be Self, which only has instructions to do message sends and read particular VM registers; which boil down to calls and pushes respectively. That part of the semantics of the proposed language are closer to Smalltalk heritage than Lisp; the expression orientation, syntax and, at lack of a better term, "nesting" are the Lisp influence. Say, Smalltalk provides variable declarations at the start of a method, we intend to provide LET/LETREC forms instead.

I would agree that CLISP bytecode would be heavier; this approach ("template compiler"?) has been used as a baseline JIT in e.g. Jalepeño for the JVM with some success, but being a baseline JIT it is not intended to be that fast either.