This has been stated many times already, but ok, here were go again. You don’t need to rewrite code.
If you have code that runs slower than it does in old VM, you can report this as a bug. If you have code that doesn’t run as fast as you’d like, we can look at what the performance problems are. If your code has a performance problem with for loops due to use of next or localized pairs, we can implement an optimization for this. As stated before, all code we’ve looked at so far doesn’t do either of these.