I use PFPX, and I keep a Navigraph Ultimate subscription so my AIRAC is current. Plus I have an FS Aerodata subscription keeping my P3D v4 world navdata current.

In my case, I have never had a "crazy" flight plan using PFPX.

Still PFPX normally would not be giving "crazy" plans even with outdated data, especially on approach; just because an approach is old does not mean its crazy. 😃

You may want to check for any planning restriction settings that you may have set in PFPX. Also, I suppose if you are removing discontinuities where vectors would be given, this can in some cases lead to some very tight turns that the 747 cannot accomplish even at Flaps 30 +5 speeds. 

But I think that my original answer applies to the original question. The STARS into KJFK don't have any speed restrictions below 250 kts and the FMS will rely on the pilots to slow the plane down according to safety/ATC instructions. Once that happens you will see the Magenta line will be more sensible/possible on approach.  

 

you are all quite right, waypoint wise, I neglected to mention that was going to land on the 4R, but ATC told me 13L hence the AROKE waypoint.

11 hours ago, Contactdepture said:

you are all quite right, waypoint wise, I neglected to mention that was going to land on the 4R, but ATC told me 13L hence the AROKE waypoint.

Using default ATC?  At a place like JFK the default ATC is just about the worst thing you could add to your simulation experience.  Watch the traffic flow on FlightAware or FlightRadar24.  Note that most of the time when landing SE that they are all flying the VOR(GPS)13L/R approach.