I absolutely don't buy that argument, because everyone knows that processes are way more heavyweight and inter-process-communication is way more complex with processes than with threads. Using processes is a good way when you fear that some threads might crash (but the heck, why should they? how about writing software that is less prone to crashing) but not to make anything faster or more responsible. If you want that, then optimize the architecture, like, assign each tab its own JS thread, and suspend threads of tabs that are not visible. But I fail to see how processes are the magic recipe for repsonsibility. Just because Chrome does it, it does not mean that the responsiveness of Chrome is due to the fact that they use processes. They could just as well use threads and noone would even notice the difference (apart from tabs crashing the whole browser then).