This is interesting, and might explain why nobody at FSDT was ever able to reproduce this, since we don't run with many other addons (and most of the time, with none), but it's not very good news because, there's not much we can do to defend ourselves against other addons spamming the sim and taking all the available processor time and clobbering the Simconnect communication channel.
Since GSX runs entirely under Couatl.exe, Windows should already be able to distribute the load on a different core the sim runs under (especially if the one used by the sim is already at 100%) but, of course, it depends also on what the other processes are doing, either other addons, but also other running processes not releated to flightsim so yes, in such cases, tweaking the Affinity mask might help.