Considering that optical networking is still in early stages of its evolution, optical burst switching (OBS) is recognized as the most feasible data forwarding mechanism for the next generation Optical Internet. In OBS, data are forwarded in the form of a burst of packets; these bursts are assembled and disassembled in the electrical domain, in order to overcome the barrier of non-availability of optical memory. The purpose of this paper is to highlight composite burst assembly as means of overcoming adverse effects of higher burst sizes on queue delay, when aggregate selfsimilar traffic is present within the electrical domain. Such a situation would be found in an environment using Differentiated Services (DiffServ) architecture. We present an analytical model indicating negative effects on performance by larger burst sizes. Simulated results are then presented to highlight the benefits of using composite burst assembly approach in the presence of bursty traffic. Further, we highlight the benefits of combining a lower real-time class traffic utilization threshold with composite burst assembly for higher performance gains in aggregate, class-based traffic environment.