On 2/28/2023 at 9:34 AM, MammyJammy said:

On P3D 5.3, give it as many cores as you can and leverage the far more granular affinity mask to keep the virtual cores adjacent to the Thread Schedulers off.  This will most visibly improve scenery loading versus HT off with similar-if-not-identical FPS results.

I'll disagree, going above 8 cores in P3D V5.3 will increase the scheduler load and waste cache resources to the point it will saturate the main core for no benefit.  Agree P3D will use all the cores when fetching terrain but it'll be fetching redundant data (confirmed by LM). Take a look at Process Monitor on the prepar3d.exe and do a File Summary. 

Completely agree on the Random read/write importance, but there are other factors such as Windows OS File Caching and the lazy writer process and FlushFileBuffers.

With that said, setting affinity to external processes like Chase Plane, AIG Controller, HiFi Weather, etc. so there could be some benefit to going beyond 8 cores.  

Most CPU's with 6 or more real cores will see a benefit with SMT (AMD) or HT (Intel) OFF.  AMD has other considerations also such as staying on CCD0 only pending core count usage (even more relevant with 3D vCache).  Intel's eCore and AMD's 3D vCache have introduce more complexity to the quest for optimal performance over any given application/game in a given OS version.

Soooooo...

After a lot of tweaking, I have something that runs a stable 60-ish FPS on average, with areas like KBWI dropping down to the 30-ish but, even there, remaining stable. 

On 2/28/2023 at 12:34 PM, MammyJammy said:

For your CPU, I'd encourage you to try giving it as many cores as you can and mask off the HT cores for the Thread Schedulers.  Try this:
https://izn-flightsim.s3.amazonaws.com/affinity.html?cores=8&threads=16&affinity=63447&coreAffinity=63444&mainThread=0&renderThread=6&frameThread=1#presetAnchor

This is the current Job Scheduler/Affinity Mask that I'm using, as well as using FSUIPC to mask off ActiveSky and ChasePlane. I've done a lot of fiddling with NVIDIA through its control panel, as well as tinkering with the settings in P3D itself...and I do mean a lot of fiddling and tinkering.  At this point, I'm running what I feel to be reasonably high graphics settings, and reaching a 99% GPU Core load, too. Along the way there have been some quirks, the major one being having the FPS immediately drop by 50% the moment I undocked any window or panel. The cause of that seems to be attributable to several factors.  One is installing Geforce Experience. To correct that one I needed to uninstall the NVIDIA driver, reboot, then do a clean install. Two others are Low Latency Mode and--quite surprisingly--Max Frame Rate. Both are set to global off. 

I want to thank everyone who dove right in to help me. Very much appreciated!