> the entire eval function is now too big for PGO on MSVC

I don't think that the issue is specific to MSVC. If a function becomes too big, it becomes less efficient for CPU caches.

One idea would be to move the least common opcodes into a slow-path, in a separated function, and make sure that this function is *not* inlined (use Py_NO_INLINE macro).

@Mark: What do you think?

Maybe we can keep current targets in the big switch, and call the function there. Something like:

TARGET(DUP_TOP):
TARGET(DUP_TOP_TWO):
(...)
   ceval_slow_path();
   break;

_PyEval_EvalFrameDefault() takes around 3500 lines of C code.