The performance was poor enough for long enough (and continues to be, probably?) that more than one third party implementation came along to replace it. There's

The performance was poor enough for long enough (and continues to be, probably?) that more than one third party implementation came along to replace it. There's no real reason that NPM can't be as fast as Yarn, except that it isn't (or wasn't? I haven't used it for enough full-size projects lately that I would know whether or not it's gotten better).