"with" is dangerous, because it makes it impossible to tell lexically whether you're assigning to an object or to a global variable. If you mistype a variable or pass an object of the wrong type in to "with", you can find yourself with very difficult-to-track-down bugs. In practice I'd only use it with a bunch of assertions, which could bloat the code significantly.

Chris Double suggested another alternative over on Proggit: tailcall to window.setTimeout with a delay of 0. This is effectively a trampoline; the continuation gets pushed onto a timer, the eval function returns, then JavaScript picks up again where it should. As a nice side effect, it gives the browser's event loop a chance to run, which eliminates any chance of locking up the machine. Pretty elegant solution, though I'm guessing there's a significant performance penalty.