I feel a little less idiotic knowing I have a comrade in confusion (Hi, Ca11SignPatriot!).
In the world of Arma III, where military conflicts, large-scale engagements, and sporadic firefights exist, your choice of weapon as an operator varies extremely. Here is a list of arma 3 weapons that will help you single out the most effective weapon for your next mission. Titan MPRL Compact.
To my knowledge, I am not running any such overlay or recording software (and I'm pretty sure I would know). I've been playing Arma 3 on my Dell Inspiron laptop - I'm lucky to get 30 FPS on 80% sampling and practically everything else set to 'low' or 'off.' I can just imagine what would happen if I tried running recording software. I also just did a reinstall of Windows 10, so I doubt it's an issue with a bloatware program I'm not aware of.
Steam does have an in-game overlay feature. I have it disabled though. Is it possible that it's not really turned off (just inaccessible from in-game)? I should try running Arma 3 without Steam... never tried that before, or even considered that it was possible, though now that I think about it, why shouldn't it be?
I am swamped for the rest of the week, but I will try to get it working on Saturday and attach the debugger. As always, thanks again for your patience with this issue.