This makes no sense. Interpreters add indirection at every single statement in the program. The fact that they may know the direction of the occasional branch cannot possibly make up for this.
No. A JIT is a valid strategy for a scripting language implementation. An interpreter is a different thing. Many JIT compilers use an interpreter for running uncompiled code and profiling ("mixed-mode interpreter"), but "interpreter" and "JIT" are in no way synonymous.
