The assertion that JSON parsing is faster than I/O for most applications does not match my experience. First, achieving 10 GB/s consistent throughput for I/O on

The assertion that JSON parsing is faster than I/O for most applications does not match my experience. First, achieving 10 GB/s consistent throughput for I/O on a server is pretty ordinary these days. If your systems are designed for performance and efficiency, parsing JSON with throughput that will saturate the I/O capacity is a challenge. Second, a lot of JSON that gets parsed in applications isn’t transiting I/O at all, it is in memory and only a subset of what is parsed may transit I/O. In these cases, there is an even higher bandwidth threshold for peak performance — memory bandwidth. I’ve profiled many applications that were completely and thoroughly bottlenecked on JSON parsing, even when care was taken to not be profligate with JSON parsing because everyone knows it is quite slow.