Just wanted to add my voice to those that Windows 8.1 fixed a lot of issues for, I was able to play the game somewhat reasonably until patch 2(suttering and fps drops I had before, but they were manageable) but patch 2 made it completely unplayable since it used 100% cpu usage nearly all the time, but now after updating to windows 8.1(yes I did it just for this game:P) my cpu usage sits at about a steady 50-60% while playing(strangely the cpu usage is at 80%ish when just sitting on the main screen before loading in to the game, and if I alt tab while in game the cpu usage will skyrocket aswell, which I guess it just a Bioware hallmark since DA:O and DA2 and ME1 do the same across 3 different PC's for me). And I have a solid 60fps without any real drops where as before I would quite commonly drop to to 40fps.
Thanks a lot for your input, Naroth! It's true that I upgraded from Windows 7 to Windows 8.1 Pro myself just so that I can play DA:I better and to this day I do not regret it in the slightest! All of the incessant and unexplained stuttering simply went away after the upgrade and I could also run on higher settings as well. To anyone who was thinking of upgrading but was not quite sure, I can recommend it 100% from personal experience. I also only paid 25$ for a genuine key, so that was even better! 
With 16gb of RAM, you really do not need any virtual memory, unless you care about windows crash dumps. If you care about crash dumps, then you need like 400mb of virtual space for windows to create the dump. If you are creating a 10 gb ram drive or using the majority of that memory for something, then it might be a different story.
Even with 16 Gb RAM, there are programs that can have trouble running without any virtual memory, such as older PC games for instance. This is the reason I recommended that everyone should have at least 1024 Mb of virtual memory, just in case. 
Regarding the upgrade to Windows 8.1 I would be willing to try a trial version at some point but I am too nervous with all the incompatibility issues I have heard about, especially SweetFX that I use with ALL my games (when available.)
I changed my VM to 1024 - 4096 just to be sure! I have just played for an hour and I didn't have any game breaking problems. But I have noticed that the game is suffering some really bad freezing every few seconds though which is very off putting. It wasn't nearly as bad as before the patching. So basically whilst in combat and just simply running around the game will freeze for a second then resume. I ran HWM and Resource Monitor and alt-tabbed to check what it was up to and took a screenshot which I will link. I think things look OK? I have noticed the CPU does spike up towards 100% every now and then though it isn't evident on the screenshot. Other times that I have tabbed I have seen it spike though.
http://i.imgur.com/JwRLs20.jpg <--- RM screenshot. I also saved the HWM as a text file that I could upload too.
I will keep playing when I feel like it but will monitor it closely. A shame that I feel I can't fully enjoy the game because I have to watch it's performance so meticulously. It really takes away from the experience. But I honestly feel I shouldn't settle with it being the way it is. Again thank you for all the help so far.
Indeed, SweetFX has a lot of problems running with Windows 8.1 due to its upgraded WDDM package for DirectX, which is actually what makes Windows 8.1 significantly better for gaming than Windows 7. I know you're reticent about upgrading, but trust me - it's absolutely worth it. Your games will perform better across the board, everything is much snappier and with Classic Shell you won't even know you've moved from Windows 7! 
I know exactly what you mean about not being able to enjoy the game due to constantly monitoring its performance, since I always did that during my 140+ hour playthrough so that I might test things out for the OP guide. My advice to your as a PC gamer is this: never settle for poor performance, always strive to get more out of your machine and games. That's the whole beauty of PC gaming and rest assured, every problem has its solution. In your case, I'm 100% sure that upgrading to Windows 8.1 would substantially improve your gaming experience across the board. 