This paper presents an algorithm for drawing a sequence of graphs online. The algorithm strives to maintain the global structure of the graph and thus the user's mental map, while allowing arbitrary modifications between consecutive layouts. The algorithm works online and uses various execution culling methods in order to reduce the layout time and handle large dynamic graphs. Techniques for representing graphs on the GPU allow a speedup by a factor of up to 8 compared to the CPU implementation. An application to visualization of discussion threads in Internet sites is provided. Categories and Subject Descriptors (according to ACM CCS): I.3.8 [Computer graphics]: Applications H.4.3 [Information systems applications]: Communications applications