Subjective. In my opinion, the physics of electrophoretics imposes a minimum latency that no body will be able to surpass unless they change to new yet-to-be-invented materials or create new laws of physics. 700ms for a clean greyscale update in 2006 has remained 660ms in 2022. Sure, there's various tricks degrading to 1-bit dither like A2 with Dasung but it the core apple to apple comparison proves physics remains the unsurmountable bottleneck. Some users can tolerate that kind of latency for some purposes. Document editing is a good example. 700ms is fine for that. Such a "laptop" is possible. But a general purpose laptop? A basic proof, add a usleep(700*1000) to foo.flip() and see how your user interface feels. If you can tolerate it, then such a laptop could be available for you.