It compromises performance in a similar way to using any byte code vs final machine code. It remains to see how much of a VM support will be required to make this work, as that's typically the large overhead cost of using non-machine code.
If anything the same exact FSAIL will run faster and faster on the same exact hardware as newer JITs come out.
If anything the same exact FSAIL will run faster and faster on the same exact hardware as newer JITs come out.