Do we need an interpreter or a fast code generating, zero optimizing JIT? I can think of advantages to each approach. Assuming a C/C++ implementation, a traditional interpreter is easy to port to a new architecture and we can populate Execution Engines (EE) for different platforms rather easily. On the other hand, a fast code-generating JIT can call runtime helpers and native methods without additional glue code whereas an interpreter has to have special glue code to make it work in a JIT environment. Needless to say, if a method is called more than once, the one time cost of JITing without optimization may be lower than the cost of running the interpreter loop. Our experience is that a fast, zero optimizing JIT can yield low-enough response time. So, I think at least Harmony has the option of having a decent system without an interpreter. Thoughts? Steve Liao, Intel Managed Runtime Division