What part of the computing hierarchy can be most improved?

In terms of hardware, systems software, end user software. I think higher level software is an area that can be improved greatly but Im curious if there are any opinions on the lower levels of the compute stack.

Perhaps the hardware landscape we're in is a shallow minimum that we're just stuck with. Perhaps other computer architectures like Lisp would allow much more efficient hardware in general?

Perhaps OS's and high performance libraries are designed badly leading to inefficiencies all round?