It very well might be that gap has grown, though I think the expectations of optimizations of the code has grown too. On the other hand, we now have more cores than we know what to do with, so an interesting approach would be to start generating code, and inserting calls to the code generator for pieces that hasn't been generated yet, and farm out generation to multiple cores.

If the code is structured right, and you could certainly try to sort the code based on a dependency graph, you don't even need to load the entire file before you can start generating code from SDE (but you'd need to be prepared to stub out forward jumps so they point to something that'll generate or wait for generation of the rest where necessary).