A first instance of a managed runtime environment is provided. An optimized version of a code unit and a corresponding set of one or more speculative assumptions are received at the first instance of the managed runtime environment, wherein the optimized version of the code unit produces the same logical results as the code unit unless at least one of the set of one or more speculative assumptions is not true, and wherein the optimized version of the code unit and the corresponding set of one or more speculative assumptions are generated by an entity that is different from the first instance of the managed runtime environment. The optimized version of the code unit is executed at the first instance of the managed runtime environment. Whether the set of one or more speculative assumptions hold true is monitored at the first instance of the managed runtime environment.