Dynamic graph summarization is the task of obtaining and updating a summary of the current snapshot of a dynamic graph when changes (edge insertions/deletions) occur in the graph. As real graphs are massive and undergoing lots of changes, we need dynamic summarization algorithms that scale and are able to respond rapidly to changes in the graph. In this paper, we present two algorithms for lossless summarization of dynamic graphs. We first give an algorithm (Optimal) that is able to obtain and dynamically update the smallest-possible-anytime lossless summary in terms of node reduction. We achieve up to 8 orders of magnitude running time improvement over batch counterparts, and up to 12x improvement over the state-of-art in dynamic graph summarization, while at the same time offering up to 6x improvement in node reduction. We then present an even faster lossless summarization algorithm (Scalable), which goes further into speeding up dynamic updates by offering an additional order of magnitude improvement over Optimal at the cost of having lesser node reduction. Extensive experiments show that Scalable offers node reduction rates that are close to those of Optimal for many datasets. As such, Scalable is a preferred choice when speed of change is very high.