Final rendering is one of the tasks that could be split between multiple parallel threads easily. That is why no wonder that the new Pentium Extreme Edition 840 with two physical cores and Hyper-Threading technology provides a pretty significant performance boost. Although to be fair we should say that this performance increase is still not enough to outpace Athlon 64 X2 4800+.
The performance increase during final rendering in Lightwave depends a lot on the type of image. In some cases the sue of Pentium Extreme Edition 840 can speed up the rendering process a lot, however, there are a few scenes where this processor runs as fast as the single-core Pentium 4 solutions.