To build conversational robots, roboticists are required to have deep knowledge of both robotics and spoken dialogue systems. Unlike using stand-alone speech recognition/ synthesis toolkits, a cloud robotics platform for humanrobot communication enables high-quality speech recognition and synthesis that is optimized to human-robot interactions. This is challenging because we need to build a wide variety of functionalities ranging from a stable cloud platform to highquality multilingual speech recognition and synthesis engines. From this background, we constructed rospeex , which is a cloud robotics platform for multilingual spoken dialogues with robots. Over 20,000 unique users have used rospeex in the two years since it was launched. In this paper, we propose a method to reduce the response time in rospeex; and analyze its effectiveness. We also analyze the server logs of rospeex that we have collected.