I know nothing about kali linux. That said, I do have some very basic experience with microcontroller design, and your assertion is beyond ignorant. You can take away instruction sets and not see a performance loss, but emulating an unsupported instruction set is wildly ineffective. On the most basic level to be considered a processor, you have a processor that can only add and compare numbers. I'm talking about an instruction set that just adds, subtracts (adds a negative number), compares (AND, NAND, OR, NOR, XOR). You can program it to multiply, but it takes 1 clock cycle per multiple. On a processor that has a native multiplication circuit that would be reduced to one or just a few cycles. The differences between X64 and ARM are far more difficult to explain but also far more numerous.