X86 has some inherent disadvantages to arm and other newer risc architectures. The main one being that modern x86 is actually a risc architecture with a x86 to

X86 has some inherent disadvantages to arm and other newer risc architectures. The main one being that modern x86 is actually a risc architecture with a x86 to risc conversion layer. Pure risc architectures like arm do not pay this tax. There are other reasons as well. For example, the lack of many registers in the isa exacerbates the register renaming cost. Jim Keller estimates that fully developed arm chips would be ~15-30% more efficient than their x86 counterparts.