@andreaskviby
Sadly, yes, it would seem so. No updates in two years, no responses from developer in a very long time.
An alternative we use is Query Monitor. It works a bit differently, but can help you find what plugins may be slowing down your site. It gives you a way to easily see errors, slow DB calls, repeated DB calls, DB calls by plugin, and a lot more. Using that with WP_DEBUG is an excellent way to see what plugins may be slowing down your site. Actually, it’s a bit more of a scientific method, so in that respect it was always better than P3, since P3 never showed the real cause of the issue.