Wow, this is really strange, man. Minecraft is not greedy on resourses and is pretty well optimized, so there should be no problems at all. Even computers with much worse specs can run this game. I think that the problem is software related. There must be some bad drivers or system errors. I would suggest reinstalling drivers, directx, vcredist and all stuff like this. I have recently read some articles about minecraft on https://www.ethershock.net/ and wanted to play this game too. I had a pretty low fps, but this manipulations have helped me to get rid of them. I think that it should help you too.