I think this explains all of the issues you are having. This low framerate is likely causing the issues with the downlink as well as that difference in k-factor .Also, my frame rates sit around 11-13 fps.
Eureka! I think that was the problem.May I ask what you are running orbiter/NASSP on specification wise?
Happy you are enjoying it! There are endless possibilities as you are sort of seeing (being able to fly a mission using just the actual flight plans etc)I'm not a computer guy (in case you haven't gleaned that) but if I understand what's going on in NASSP, you guys have taken the actual code that the CMC and LGC used, modeled the actual RTCC, and somehow figured a way to run it all on Windows. Then added all the systems simulations (which boggles me). And put together all the graphics and textures etc. and then come up with a way to incorporate it onto the Orbiter platform. Which I'm sure way over simplifies what's actually going on.
But I'm continuously amazed with NASSP. If my bottom-feeder laptop can run the simulation (with an occasional hiccup) at all, then the whole program must be constructed pretty well. If I had even an average computer this issue would never have cropped up.
It's been great using NASSP.