I have a 970 dont see any performance issues with Vram going over 3.5?

 

its subtle, but its there, I got one too.

Another GTX 970 data point here:

 

System: i7 6700 4.0 GHz, 32 Gig RAM, running Windows 10

Monitor is at 1920x1200 resolution

Threaded Optimization Off in Nvidia control panel

 

X-Plane settings:

Visual Effects - High (HDR)

Texture Quality - High

Antialiasing - 2X SSAA+FXAA

Number of World Objects - Maximum

Reflection Detail - Minimal

Draw shadows on scenery - Off

 

With that setup, I'm getting frame rates of 40 fps or better, over most of the scenery I fly. Sometimes it dips down to the mid 30's over a dense urban center, but never below 30 fps. It shoots up to 50-60 fps over ocean or clear sky over a cloud deck. I could probably bump one of those graphics settings up a tick or two and still stay above 30 fps, but I like having 40 fps as my usual lowest frame rate. It's just comfortable overhead. I'm keeping an eye out for Nvidia's next series of cards, but I'm happy with what I'm getting in XP11 on my GTX970 for now. I'll upgrade when I see something with 8gb VRAM where the price is right. 

 

If the OP is getting such drastically lower frame rates, I'd suspect either Threaded Optimization is on, or there are too many resource hog apps running in the background. I do try to keep my system fairly stripped-down for extraneous apps that don't need to be running all the time.