Windows, Linux or OSX? I'm curious because on Linux, threads and processes are essentially the same thing - they're the same data structure in the kernel. But as far as I know, that is not true on Windows. I also find his conclusion a bit disingenuous: I never have more than ~10 tabs open. I'm more interested in the performance around my actual usage, not an order of magnitude more.
Of course the more sane model is for a process to be an address space container, and threads to be associated with a particular process, but when discussing them, that particular implementation detail is moot.