Folks tend to think Minecraft is a low resolution game thanks to all those big blocks. It's not and if you crank the settings up you can pose a SERIOUS challenge to your rig. Not surprising at all to me that Minecraft would generate a lower or similar framerate as BF4 - for instance I run minecraft at about 40FPS (it's the quality settings I like best like view distance, shadow, fancy water) and World of Tanks also at 40 FPS.