First off, my system:
Intel i5-2400 @ 3.2 GHz
NVidia 560 TI
8 GB RAM
Windows 7 Home Premium
Even if putting the graphical fidelity of Divinity to an absolute minimum, my system isn't able to display the game in more than 45-50 DPS, with occassional dips down to 30 FPS and sometimes even 10 FPS. Other games (tested: Hearthstone, EVE Online, Kerbal Space Program, Civilization V) run solidly on 60 FPS with their respective graphical options at maximum. All games are played in a resolution of 1920x1200 pixels. I have no real explanation why especially Divinity is tanking, as other people with comparable setups have reported to me that their games are running fine for the most part.
Your computer specs are extremely low end. It would be a stretch to even consider them mid-low end.
The i5-2400 is extremely out-dated and it is a very slow processor. Does it work? Sure. For games such as this one that have very high amounts of graphics for your CPU to send to your GPU, it just won't cut it. For comparison, the AMD FX-8350 is nearly 2x as fast as your current processor.
You definitely need to upgrade your system specs. If you don't like AMD, then check out the intel i5-4670k. It runs for around $219.99 and it is an ~50% increase in performance over your current CPU.
I also have to say that 8gb of RAM is quite low these days... I also have to assume that your RAM is not very fast, but I could be wrong.
Your video card could also use an upgrade. A ~$150 (sale) Radeon HD 7870 has about 10-15% more performance than your video card. Your card is not terrible but could use an upgrade, just my opinion.
Always be sure to purchase adequate cooling for your CPU and ventilate your case.
tl:dr This is not a problem with the game. Your CPU/Computer Specs are out-dated for current gen. Could the game use some more optimization? Probably. Yet still, your computer's specs are out-dated.
