What kind of RAM does your system have and what's allocated to FTB? The processor might be trying to shuffle things around the RAM as one or the other demands more than it's getting/you have.
As for processors, it doesn't really make much difference AMD vs Intel. Yes, there are people that will squeal about 10FPS. Loudly, and so consistently, you'll start to believe anything but a bleeding edge Intel is so much aluminum foil. It's complete nonsense. Look at that link for a moment though. The top processor cramming 10 more FPS on? That's a thousand dollar processor. It's closest AMD competitor? The one only 10 FPS behind it? $200. So yeah, clearly those ten FPS are worth the price of an entire additional computer.
Of course the next Intel on the list is only about a hundred dollars more than the AMD, and does get better FPS, but you'll never stop getting people waving that 10 FPS in your face.
AMD overclocks better unless you pay extra. Intel loves to sell models you can't over clock, where you can overclock any AMD. But for your theoretical overclocking, the FX-9590 already runs 4.7Ghz so it doesn't have to be overclocked to meet what you're after.
Now, all that said... can your monitor even display better than 60FPS? Can you tell the difference without an FPS counter? I don't start to see a difference until the count drops below 20FPS, but perhaps that's just me. 60FPS is probably a lot more than Minecraft needs since it's not a twitch shooter. Still, RAM might be more at issue than your processor.
Please don't get me wrong. Despite what many people believe, I think AMD chips are perfectly fine for gaming. I was just tossing some facts out there. Although, it is worth noting that the FX-9590, no matter which way you look at it, is a very bad buy. There are high end GPUs that consume less power than it does, and it requires both a good CPU cooler and a beefy motherboard(The 9590 has been known to make el cheapo AM3+ boards burst into flames.) Between the cooler, CPU, and board, you are looking at ~400 dollars. For reference, an i5-6500 and motherboard to go with it would run you ~260 dollars, while also providing superior gaming performance and using a lot less power. The 9590 was never a good buy, not even when it first came out. In single threaded performance, even a fifty dollar Pentium stomps on it. And in multi-core, unless your application is highly optimized for AMD's architecture, a similarly priced i7 build would knock a 9590 out of the park in value, performance, and efficiency.