Alright, did some work last night--all in the name of 7 Days, mind you, because this game is super awesome
I discovered that my SATA controller (BIOS) was set to RAID, so switched that to ACHI. I've also ordered an SSD drive which should arrive in a couple days, thanks for that suggestion!
I validated the 7 Days files in Steam, but went ahead and uninstalled/reinstalled just in case.
Updated my GeForce driver using the "clean install" method and un-ticked GeForce Experience and 3D Vision stuff.
Xbox and Game Mode stuff has long since been disabled.
I switched my system page file from 40GB to "system managed" (4GB)
Already had the root Steam folder in the Trend Micro exclusions list, and I play with the service "muted" anyway. BTW, your instructions for this are for the enterprise version of Trend Micro, not the consumer, but same general rules. Though, there's no "enable exclusions" option in the consumer prouduct, you just add the folder and it's supposed to work.
After doing all of this, I switched vsync mode to "adaptive (half)" in Nvidia cp and enabled triple buffering. I've also noticed that the "ASR smoothing" in the Nvidia Profile Inspector seems to help jitters in this game a whole lot, which is strange because it's meant for SLI systems. Enabled that as well. I recall having done quite a bit of tuning in the global options for Fallout 4 a while back, so I'm wondering if those impacted performance?
Also, uninstalled Rivatuner and Afterburner per-recommendations--I was using the FPS limiter to try and fix some controller look-speed issues when the frame rate dipped.
I'm happy to say after all of that, things work pretty well now. Getting 90-120 FPS without any controller speed issues at 120Hz (I play on my TV). Still unsure as to why using vsync adaptive/half in the Nvidia CP and leaving Vsync on in game (both enabled) seems to be the best combo, but there it is.
Will report back after I've had some more play time. Haven't built a new base yet or had a horde attack, but things feel a lot smoother now.
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Is there a guide to specific Nvidia CP tweaks for this game anywhere?