A little update.
I got the GPU today. A gigabyte GTX 770 OC 2gb.
My old one was a Gigabyte GT 560 TI 1 gb
The rest of the system atm is an i7 2600 @ 3.4, 16gb ram and DCS on SSD.
I set all settings to max. Everything.
I then loaded a clouded mission with tons of moving units around me.
With old GPU: 5 FPS
With new GPU: 20 - 25 FPS
I am waiting for a new CPU, an i5 3570k. My next tests will be with new cpu at standard clock, then OC to around 4.2 ghz.
All in all I am happy. I never expected that I could run on max settings, but this test was to see how big the GPU upgrade was. And it was imo big.