portable runapp for non portable exe

It is possible. Actually I'm thinking about it for some time. One solution is using virtual machine. But it's slow and big. There is a better solution, unfortunately if thread safe - it is also slow. But for most apps it would work.
Disadvantages:
1. Some things needed are hard to write. I'm developing such code for different purposes.
2. There's a lot of easier things to write. I won't write it - I won't find enough time.