I think that worst case 2x, average case 1.5x is attainable.

- Code that uses SIMD or that is mostly dealing with primitive data in large arrays will get to close to 1x

- Code that walks trees and graphs, like interpreted or compilers do, might end up north of 2x unless I am very successful at implementing all of the optimizations I am envisioning.

- Code that is IO bound or interactive is already close to 1x