We show how to increase locality of object-oriented programs using several heaps. We introduce the notion of sandwich types which allow a coarser view on objects. Our idea for increasing locality is to use one heap per object of sandwich types. Performance measurements demonstrate that the running time is improved by upto a factor 5 using this strategy. The paper shows how to derive sandwich types from classes. Thus, it is possible to control the allocation of the different heaps using compile-time information.