Sorry, I may be missing the point here, but reading that page doesn’t immediately make it obvious to me what that feature is. Is it some constant time execution mechanism that you can enable / disable on a per-thread basis to do… what exactly?
Last I saw, it seemed like the plan was to unconditionally enable it, and on the off chance there's ever a piece of hardware where it's a substantial performance win, offer a way to opt out of it.
This link seems broken. Some searching suggests that the title and slug may have changed, but I haven't found a working link to the article. Just from the title alone, I am extremely interested in reading more about this, because it's been largely mythical for a long time.