See this thread: https://groups.google.com/a/chromium.org/forum/#!topic/speed/6UwVwIdbZlY for details

For sending 144 byte string, IPC with the old IPC::ChannelWin takes 32us while Mojo takes 39us. IPC layered mojo takes 59us. Maybe we don't care about the latter case since it's temporary and there'll be overhead of layering. It would be nice to see if we can say that for the average IPC, Mojo isn't slower (that might mean the 144 byte string example isn't realistic, so finding out a better example).

Here's a cl that brings back IPC::ChannelWin for testing: https://chromium-review.googlesource.com/c/572140/