One thing that I forgot to mention before was that I was messing around with the Nvidia Control Panel settings, and I noticed that in certain situations (like when I was testing fps while stripmining in a cave), when I selected Minecraft to use the Intel HD graphics it would give me MORE fps than when I selected the 1070. E.g. in a cave stripmining I would be getting maybe 500fps when using Intel graphics and in the same situation I would be getting around 350fps on the 1070. Any thoughts on this?
It is possible that your frame rate is limited by data transfer speed between components.
Rendered frame from dedicated GPU must be copied to system memory through PCIe bus which is slower than the link between iGPU and system memory.
Maybe your laptop has 8-lane PCIe connection to GPU while some other laptops have 16-lane PCIe connection.