Object oriented programming environments frequently suffer serious performance degradation because of a high level of paging activity when implemented using a conventional virtual memory system. Although the fine-grained, persistent nature of objects in such environments is not conducive to efficient paging, the performance degradation can be limited by careful grouping of objects within pages. Such object placement schemes can be classified into four categories --- the grouping mechanism may be either static or dynamic and may use information acquired from static or dynamic properties. This paper investigates the effectiveness of a simple dynamic grouping strategy based on dynamic behaviour and compares it with a static grouping scheme based on static properties. These schemes are also compared with near-optimal and random cases.