Any special tweaks I need to apply here?
It is a Logitech wireless G602. I've had it for quite some time, and not had any conflicts previously that I am aware of.
No change with the defaults in NVidia control panel. Still slow unfortunately.
I have left Geforce Experience installed for now, as it's the older version (pre 3.x) and I prefer it to the new one that requires a login to connect and download drivers.
The Logitech wireless mouse may well be what is causing the problem. Logitech mouse drivers seem to cause problems with GameMaker games in general, as far as I can tell; you might try switching to a wired and/or non-Logitech mouse and see what happens. Lowering the poll rate on the mouse may also help. I will keep investigating the issue.
That is drastically improved, though still very sluggish...that is so weird, this is the first time I've seen it drop in performance because of permissions. To further increase performance, you could try moving its directory over to your other drive, and also mess with compatibility settings by right clicking the exe file and opening properties. My computer thinks it should run in compatibility mode with Windows XP Service Pack 2, which is probably because GameMaker 8.1 is a dated engine at this point, though I have never had the performance drops you are facing.
Is the drive it is currently on a solid-state or regular hard drive?
Thanks very much for helping me troubleshoot it.
It is a game called Venture Forth.
http://store.steampowered.com/app/501310/
They did recently release a couple updates that have resolve the major performance issues. I don't believe it's a Gamemaker title though.