This is a design sketch for an adaptive optimizer implemented in Smalltalk above a conventional "jitting" virtual machine with "minor" extensions. Adaptive optimization as we are discussing it here was invented by Urs Hölzle and is described in [Hölzle94]. The sketch is far from complete, focussing instead on the interface between the optimizer and the virtual machine, hence outlining a potentially portable architecture where an optimizer written in Smalltalk can be hosted above a range of specific virtual machines. This portability is intended to allow us to collaborate on the project without having to define and implement a common vm, with all the difficulties of migrating current systems to a new VM, allowing us to apply the optimizer within our current systems. Of course, this architecture still requires significant extensions to the execution machinery of extant VMs but these extensions amount to something far from a rewrite.