I've been getting quite a bit of lag while moving around, but when I stay in one play my FPS maxes out at about 370 FPS. I did some testing and limiting the FPS to about 80 helped a little, but I am still getting quite a ton of FPS lag while moving around and placing blocks.
I have the same issue as you. I also have the same graphics card. I have searched and havent been able to find anything. Something i have found is that there was another guy with the same graphics who has this issue also. Idk if it has anything to do with it.
I tried many different things, mipmap off-on, v-sync (useless) off-on, render distance 2-32, simple lighting, optifine, etc. And it only runs smoothly when it is a flat world only 4 thick. And it only does this on minecraft.
Here are my specs:
AMD FX-6300 Six-Core Procesor
GeForce GTX 970
8G Ram
64 bit OS
Use
Advanced
System
Care.
Overall, your specs are really good, so making sure your drivers are up to date and working as intended is my best recommendation.
Why?
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The driver update will be coming in the future, but I am not sure when.