Tweaked non-workflow send operations.  Now the JIT will only zero initialize the Worker struct *twice* rather than many more times...  It is really funny how badly .Net JIT and especially F# handle structs.  Both generate so many unnecessary operations when handling structs that it is no wonder it is difficult to get any advantage from using structs.  Probably the only reason why the Worker struct is a big win in Hopac is that it eliminates a lot of GC work due to keeping Work items local to a thread and write barriers, when pushing to Worker, are less expensive as the Worker struct is in the stack and not in the heap.